Magnetic Therapy and Migraine Headache;
a frequency specific pulsed electromagnetic field (PEMF)
therapy and repetitive transcranial magnetic stimulation
(rTMS/TMS) research bibliography.
Pulsed magnetic fields beneficially affect migraine's
abnormal brain electrophysiology, which is present to one extent
or another in headache syndromes of all types.
Extensive research suggests there are
electrophysiological abnormalities that coexist with many
different types of neurological disease states which can be
positively affected by pulsed magnetic therapy including;
Alzheimer's, epilepsy, Parkinson's, cluster
and other headache syndromes, severe PMS and other exaggerated
menstrual related symptoms, insomnia and other sleeping
disorders, attention deficit disorder ADD, attention deficit
hyperactivity disorder ADHD, depression, schizophrenia and other
psychological disorders. We
believe PEMF effects are attributable to MoreATP, which explains
very simply the
healing effects of frequency specific pulsed electromagnetic
fields (PEMF) if pulse repetition rate approximates 10 Hz. While we are fairly sure most pulsed electromagnetic
therapies lead to enhanced ATP production through some
heretofore undisclosed mechanism, where pulse repetition rate is
within 1 Hz and 15 Hz nearly all reported effects are simply due to enhanced ATP
production.
"When
the solution is simple...God is answering." ~ Albert
Einstein
Pulsed magnetic field research suggests
that pulsed electromagnetic field therapy can reduce migraine as
well as promote sleep and relaxation in insomniacs.
Transcranial magnetic stimulation (TMS/rTMS) research has proven
for decades that pulsed electromagnetic fields safely reduce
anxiety and depression using magnetic fields that are hundreds,
even thousands of times the magnetic field density used to
produce deep, restful sleep and improved sense of wellbeing
induced through EarthPulse™ magnetic field supplementation.
Published research suggests that
human disorders of many types are related by electromagnetic
anomalies in the brain and body. The application of pulsed
electromagnetic fields of particular frequency and field
density seem to be able to safely address the problem, at
least in significant part.
Frequency Specific Pulsed
Electromagnetic Field (PEMF) Research Bibliographies:
Several
hundred pulsed electromagnetic field therapy citations contained
in our research bibliographies are linked directly to PubMed
a service of the U.S. National Library of Medicine and the U.S.
National Institutes of Health. These studies are offered for your education only and are not intended as promotional material.
See also; Sandyk R, Anninos PA
, Jacobson
JI; three pioneers of electromagnetic field therapy to
treat Parkinson's, Alzheimer's and epilepsy.
PEMF Background:
PEMF Research By
Effect:
EarthPulse research:
- Headache. 2010 Jul;50(7):1153-63. Epub 2010 Jun
10.
Transcranial
magnetic stimulation for migraine: a safety review.
Dodick DW, Schembri CT, Helmuth M, Aurora SK.
Mayo Clinic, Phoenix, AZ, USA.
- Cephalalgia. 2010 Jan;30(1):46-52.
High-frequency
transcranial magnetic stimulation on motor cortex of patients
affected by migraine with aura: a way to restore normal
cortical excitability?
Brighina F, Palermo A, Daniele O, Aloisio A, Fierro B.
Dipartimento Universitario di Neuroscienze Cliniche, University
of Palermo, Palermo, Italy.
- Neurotherapeutics. 2010 Apr;7(2):204-12.
Transcranial
magnetic simulation in the treatment of migraine.
Lipton RB, Pearlman SH.
Department of Neurology, Montefiore Headache Center, Albert
Einstein College of Medicine, Bronx, New York 10461, USA
- CNS Spectr. 2007 Dec;12(12):921-5.
Unexpected
reduction in migraine and psychogenic headaches following rTMS
treatment for major depression: a report of two cases.
O'Reardon JP, Fontecha JF, Cristancho MA, Newman S.
University of Pennsylvania, Transcranial Magnetic Stimulation
Laboratory, Philadelphia, PA, USA.
-
1: Cereb Cortex. 2008
Mar 27. [Epub ahead of print]
Homeostatic Metaplasticity of the Motor
Cortex is Altered during Headache-Free Intervals in Migraine
with Aura.
Antal
A, Lang
N, Boros
K, Nitsche
M, Siebner
HR, Paulus
W.
Department of Clinical Neurophysiology, Georg-August University,
37073 Göttingen, Germany.
Preconditioning of the human primary motor cortex (M1) with
transcranial direct current stimulation (tDCS) can shape the
magnitude and direction of excitability changes induced by a
subsequent session of repetitive transcranial magnetic
stimulation (rTMS). Here, we examined this form of
metaplasticity in migraine patients with visual aura and healthy
controls. In both groups, facilitatory preconditioning of left
M1 with anodal tDCS increased the mean amplitudes of
motor-evoked potentials (MEPs) elicited in the contralateral
hand, whereas inhibitory preconditioning with cathodal tDCS
produced a decrease in amplitude. Following cathodal tDCS, a
short train of low-intensity 5-Hz rTMS antagonized the
suppression of the mean MEP amplitude in both groups. In
contrast, the homeostatic effects of 5-Hz rTMS differed between
groups when rTMS was given after anodal tDCS. In controls 5-Hz
rTMS induced a marked decrease in MEP amplitudes, whereas in
migraineurs rTMS induced only a modest decrease in MEP
amplitudes, which were still facilitated after rTMS when
compared with baseline amplitudes. These findings indicate that
short-term homeostatic plasticity is altered in patients with
visual aura between the attacks.
PMID: 18372292 [PubMed - as supplied by publisher]
-
The clinical diagnostic utility of
transcranial magnetic stimulation: report of an IFCN
committee.
Chen
R, Cros
D, Curra
A, Di
Lazzaro
V, Lefaucheur
JP, Magistris
MR, Mills
K, Rösler
KM, Triggs
WJ, Ugawa
Y, Ziemann
U.
Division of Neurology, Toronto Western Research Institute,
University of Toronto, 7MC411, Toronto Western Hospital, 399
Bathurst Street, Toronto, Ont., Canada M5T 2S8.
robert.chen@uhn.on.ca
The review focuses on the clinical diagnostic utility of
transcranial magnetic stimulation (TMS). The central motor
conduction time (CMCT) is a sensitive method to detect
myelopathy and abnormalities may be detected in the absence of
radiological changes. CMCT may also detect upper motor neuron
involvement in amyotrophic lateral sclerosis. The diagnostic
sensitivity may be increased by using the triple stimulation
technique (TST), by combining several parameters such as CMCT,
motor threshold and silent period, or by studying multiple
muscles. In peripheral facial nerve palsies, TMS may be used to
localize the site of nerve dysfunction and clarify the etiology.
TMS measures also have high sensitivity in detecting lesions in
multiple sclerosis and abnormalities in CMCT or TST may
correlate with motor impairment and disability. Cerebellar
stimulation may detect lesions in the cerebellum or the
cerebellar output pathway. TMS may detect upper motor neuron
involvement in patients with atypical parkinsonism and equivocal
signs. The ipsilateral silent period that measures transcallosal
inhibition is a potential method to distinguish between
different parkinsonian syndromes. Short latency afferent
inhibition (SAI), which is related to central cholinergic
transmission, is reduced in Alzheimer's disease. Changes in SAI
following administration of cholinesterase inhibitor may be
related to the long-term efficacy of this treatment. The results
of MEP measurement in the first week after stroke correlate with
functional outcome. We conclude that TMS measures have
demonstrated diagnostic utility in myelopathy, amyotrophic
lateral sclerosis and multiple sclerosis. TMS measures have
potential clinical utility in cerebellar disease, dementia,
facial nerve disorders, movement disorders, stroke, epilepsy,
migraine and chronic pain.
Publication Types:
PMID: 18063409 [PubMed - indexed for MEDLINE]
-
[Cortical dysbalance in the brain in
migraineurs--hyperexcitability as the result of
sensitisation?]
[Article in German]
Stankewitz
A, May
A.
Institut für systemische Neurowissenschaften,
Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52,
20246, Hamburg, Germany.
A cortical dysbalance has a pivotal role in the pathophysiology
of migraine. Numerous electrophysiological and transcranial
magnetic stimulation (TMS) studies have investigated the
interictal excitability level in migraineurs and have shown a
consistent lack of habituation during repetitive stimulation.
There is some controversy in the current literature over whether
this deficit is based on a lowered or an elevated preactivation
level. However, the current discussion may be misguided. It
seems that multiple external and intrinsic factors influence the
level of cortical excitability and the frequency and intensity
of attacks: Habituation is specific neither to migraine nor even
to pain; the same phenomenon is found in tinnitus patients, for
example. Cortical hyperexcitability is presumably the result of
chronicity and the concomitant central sensitisation process.
Publication Types:
PMID: 18228046 [PubMed - indexed for MEDLINE]
-
-
Clinical correlates of phosphene perception
in migraine without aura: an Asian study.
Lo
YL, Lum
SY, Fook-Chong
S, Cui
SL, Siow
HC.
Department of Neurology, National Neuroscience Institute,
Singapore General Hospital, Outram Road, Singapore 169608,
Singapore. lo.yew.long@sgh.com.sg
INTRODUCTION: Although controversy exists with regard to the
presence of hypoexcitability versus hyperexcitability of the
visual cortex in migraine patients, there remain a group who do
not perceive phosphenes (P-). However, its clinical implications
have not been systematically addressed. In this study, we
hypothesize that P- patients classified as migraine without aura
(MO) have distinct clinical features. METHODS: Twenty-nine Asian
MO patients (7 men; mean age: 44; median: 45; range: 25 to 65)
were consecutively entered into the study. Visual cortex
transcranial magnetic stimulation (TMS) was performed in the
migraine interictum. RESULTS: Of the 19 patients, 19 (66%) were
able to perceive phosphenes (P+), while 10 (34%) were not able
to after repeated TMS (P-). P- patients had significantly higher
headache frequency (p=0.008) and pain score (p=0.002) compared
with P+ patients. In addition, there was significant positive
correlation of phosphene threshold with pain score (r=0.52,
p=0.02) in P+ patients. There was no significant difference
between P+ and P- patients in terms of age (t-test, p=0.6).
CONCLUSIONS: Our study is inkeeping with the hypothesis that
interictal visual cortex excitability is reduced in relation to
the severity of migraine in Asian MO patients, and lack of
phosphene perception may be related to significantly elevated
thresholds beyond the output of TMS stimulators.
PMID: 17720202 [PubMed - indexed for MEDLINE]
-
Comment in:
Unexpected reduction in migraine and
psychogenic headaches following rTMS treatment for major
depression: a report of two cases.
O'Reardon
JP, Fontecha
JF, Cristancho
MA, Newman
S.
University of Pennsylvania, Transcranial Magnetic Stimulation
Laboratory, Philadelphia, PA, USA. oreardon@mail.med.upenn.edu
Our objective is to report a coincident reduction in headache
pain in patients treated with repetitive transcranial magnetic
stimulation (rTMS) for major depressive disorder (MDD). Two
patients with a Diagnostic and Statistical Manual of Mental
Disorders, Fourth Edition diagnosis of MDD, non-responsive to
prior antidepressant treatment who were enrolled in a
sham-controlled, double-blind study of rTMS for MDD. After the
study, it was revealed that both were in the active-treatment
arm. Both patients suffered from near daily headaches and kept
logs of headache frequency and severity before, during, and
after the study. Headache pain was significantly reduced under
double-blind conditions with rTMS treatment, but returned to
baseline following cessation of rTMS treatment. Ultimately, when
receiving rTMS post-study as a maintenance intervention for MDD
(approximately 2 rTMS sessions/week), the positive effects on
headache amelioration were sustained. Headache pain is
frequently comorbid with mood disorders and has been reported as
the most common side effect with rTMS. In these subjects, rTMS
was, in fact, associated with relief of depressive symptoms and
preexisting headache pain. This indicates that rTMS may be
beneficial for both disorders in some patients.
Publication Types:
PMID: 18163038 [PubMed - indexed for MEDLINE]
-
-
Comment in:
Shortened cortical silent period in facial
muscles of patients with migraine.
Curra
A, Pierelli
F, Coppola
G, Barbanti
P, Buzzi
MG, Galeotti
F, Serrao
M, Truini
A, Casali
C, Pauri
F, Cruccu
G.
Department of Neurological Sciences, La Sapienza University,
Rome, Italy. antonio.curra@uniroma1.it
Despite intensive neurophysiological research, evidence is
lacking to show whether abnormal cortical excitability in
migraine reflects a primary cortical disturbance or reduced
control by thalamo-cortical loops. One way to contribute to the
scientific discussion on this topic is to deliver transcranial
magnetic stimulation (TMS) and test the cortical silent period
(SP) recorded in facial muscles. The facial-muscle SP is a
purely cortical phenomenon that reflects the excitability of
inhibitory interneurons, and can disclose changes in cortical
inhibition even in patients without documented primary lesions
of the motor cortices. To test the interictal excitability of
cortical motor inhibitory interneurons in migraine, we
investigated the facial-SP in patients with migraine with and
without aura between attacks. In 26 patients and 15 age-matched
controls, high-intensity magnetic stimuli were delivered with a
round coil centered at the vertex during a maximal muscle
contraction. Electromyographic responses were recorded from
surface electrodes placed over the subjects' perioral muscles.
Facial SPs were significantly shorter in patients than in
controls. The SP shortening provides neurophysiological evidence
showing hypoexcitability of cortical inhibitory neurons in
patients with migraine between attacks. Despite a possible
primary deficit of cortical inhibitory interneurons in migraine,
we favor the interpretation of a secondary disfacilitation by
hypoactive thalamo-cortical loops. Based on this interpretation,
the interictal reduced cortical inhibition documented by the
shortened SP could be considered the motor counterpart of the
reduced preactivation excitability level in the sensory cortices
purported to explain why cortical evoked responses habituate
poorly in patients with migraine.
PMID: 17574759 [PubMed - indexed for MEDLINE]
-
[Neurophysiology of visual aura in migraine]
[Article in Japanese]
Shibata
K.
Department of Medicine, Tokyo Women's Medical University,
Medical Center East, 2-10 Nishiogu, Arakawa-ku, Tokyo 116-8567,
Japan.
Visual processing in migraine has been targeted because the
visual symptoms that are commonly associated with attack, either
in the form of aura or other more subtle symptoms, indicate that
the visual pathways are involved in migrainous pathophysiology.
The visual aura of the migraine attack has been explained by the
cortical spreading depression (CSD) of Leão,
neuroelectric event beginning in the occipital cortex and
propagating into contiguous brain region. Clinical observations
suggest that hyperexcitability occurs not only during the
attack, typically in the form of photophobia, but also between
attacks. Numerous human neuroimaging, neurophysiological and
psychophysical studies have identified differences in cortical
visual processing in migraine. The possibility of imaging the
typical visual aura with BOLD functional MRI has revealed
multiple neurovascular events in the occipital cortex within a
single attack that closely resemble CSD. As transient
synchronized neuronal excitation precedes CSD, changes in
cortical excitability underlie the migraine attack. Independent
evidence for altered neuronal excitability in migraineurs
between attacks emerges from visual evoked potentials (VEPs) and
transcranial magnetic stimulation (TMS), recordings of cortical
potentials and psychophysics. Recently, both TMS and
psycho-physical studies measuring visual performance in
migraineurs have used measures which presumably measure primary
visual (V1) and visual association cortex. Our VEP and blink
reflex study showed that migraine patients exhibiting allodynia
might show central sensitization of braistem trigeminal neuron
and had contrast modulation dysfunction during the cortical
visual processing of V1 and visual association cortex in-between
attacks. In pathophysiology of migraine, these
neurophysiological and psychophysical studies indicate that
abnormal visual and trigeminal hyperexcitability might persist
between migraine attacks. The influence of migraine on cortical
neural processing is likely to extend beyond V1 and abnormal
cortical activity might lead to CSD when enhanced activation
coincides with other factors.
Publication Types:
PMID: 17886478 [PubMed - indexed for MEDLINE]
-
Transcranial direct current stimulation
reveals inhibitory deficiency in migraine.
Chadaide
Z, Arlt
S, Antal
A, Nitsche
MA, Lang
N, Paulus
W.
Department of Clinical Neurophysiology, Georg-August University,
Göttingen, Germany.
The issue of interictal excitability of cortical neurons in
migraine patients is controversial: some studies have reported
hypo-, others hyperexcitability. The aim of the present study
was to observe the dynamics of this basic interictal state by
further modulating the excitability level of the visual cortex
using transcranial direct current stimulation (tDCS) in
migraineurs with and without aura. In healthy subjects anodal
tDCS decreases, cathodal stimulation increases transcranial
magnetic stimulation (TMS)-elicited phosphene thresholds (PT),
which is suggested as a representative value of visual cortex
excitability. Compared with healthy controls, migraine patients
tended to show lower baseline PT values, but this decrease
failed to reach statistical significance. Anodal stimulation
decreased phosphene threshold in migraineurs similarly to
controls, having a larger effect in migraineurs with aura.
Cathodal stimulation had no significant effect in the patient
groups. This result strengthens the notion of deficient
inhibitory processes in the cortex of migraineurs, which is
selectively revealed by activity-modulating cortical input.
Publication Types:
PMID: 17498207 [PubMed - indexed for MEDLINE]
-
-
Brainstem dysfunction in chronic migraine as
evidenced by neurophysiological and positron emission
tomography studies.
Aurora
SK, Barrodale
PM, Tipton
RL, Khodavirdi
A.
Swedish Headache Center, 1101 Madison #200, Seattle, WA 98104,
USA.
BACKGROUND: The pathophysiology of chronic migraine (CM) is not
fully understood. We aimed to examine transcranial magnetic
stimulation (TMS) indices of cortical excitability in patients
with CM and also performed PET studies to ascertain if there
were any areas of activation and inhibition for possible
correlation. METHODS: Excitability of the cortex was assessed by
a reliable parameter of magnetic suppression of perceptual
accuracy (MSPA) profiles using transcranial magnetic stimulation
in 25 patients with CM. Of these 10 patients were also studied
with ((18)F-FDG PET) scans. RESULTS: MSPA demonstrated decreased
inhibition in CM compared to normal controls and episodic
migraine. The percentage of letters reported correct at 100 ms
was 84.37 for CM compared to 19.14 for normal controls and 57.41
for episodic migraine. The PET evaluation in 10 subjects
demonstrated increased cerebral metabolism in areas of in the
brainstem compared to the global flow. There were also decreased
areas of cerebral metabolism in the medial frontal and parietal
as well as the somatosensory cortex. CONCLUSIONS: Patients with
CM appear to be characterized by reduced visual suppression
correlating with high cortical excitability. In a cohort of
these subjects there was brainstem activation and inhibition in
certain areas of the cortex suggesting a potential dysfunction
in the inhibitory pathways.
PMID: 17635590 [PubMed - indexed for MEDLINE]
-
-
Safety aspects of transcranial direct current
stimulation concerning healthy subjects and patients.
Poreisz
C, Boros
K, Antal
A, Paulus
W.
Department of Clinical Neurophysiology, Georg-August University,
Robert Koch Strasse 40, 37075 Göttingen, Germany.
csaba.poreisz@med.ni-goettingen.de
Cortical excitability changes induced by tDCS and revealed by
TMS, are increasingly being used as an index of neuronal
plasticity in the human cortex. The aim of this paper is to
summarize the partially adverse effects of 567 tDCS sessions
over motor and non-motor cortical areas (occipital, temporal,
parietal) from the last 2 years, on work performed in our
laboratories. One-hundred and two of our subjects who
participated in our tDCS studies completed a questionnaire. The
questionnaire contained rating scales regarding the presence and
severity of headache, difficulties in concentrating, acute mood
changes, visual perceptual changes and any discomforting
sensation like pain, tingling, itching or burning under the
electrodes, during and after tDCS. Participants were healthy
subjects (75.5%), migraine patients (8.8%), post-stroke patients
(5.9%) and tinnitus patients (9.8%). During tDCS a mild tingling
sensation was the most common reported adverse effect (70.6%),
moderate fatigue was felt by 35.3% of the subjects, whereas a
light itching sensation under the stimulation electrodes
occurred in 30.4% of cases. After tDCS headache (11.8%), nausea
(2.9%) and insomnia (0.98%) were reported, but fairly
infrequently. In addition, the incidence of the itching
sensation (p=0.02) and the intensity of tingling sensation
(p=0.02) were significantly higher during tDCS in the group of
the healthy subjects, in comparison to patients; whereas the
occurrence of headache was significantly higher in the patient
group (p=0.03) after the stimulation. Our results suggest that
tDCS applied to motor and non-motor areas according to the
present tDCS safety guidelines, is associated with relatively
minor adverse effects in healthy humans and patients with
varying neurological disorders.
Publication Types:
PMID: 17452283 [PubMed - indexed for MEDLINE]
-
-
Intracortical inhibition and facilitation in
migraine--a transcranial magnetic stimulation study.
Siniatchkin
M, Kröner-Herwig
B, Kocabiyik
E, Rothenberger
A.
Department of Child Neurology, University of Kiel, Kiel,
Germany.
OBJECTIVE: Migraine is a disease of altered cortical
excitability between attacks. However, the mechanisms of
abnormal excitability in migraine are insufficiently
investigated. Hence, the aim of the study was to investigate
intracortical inhibition/facilitation of the motor circuit in
migraine. METHODS: Sixteen women suffering from migraine without
aura and 15 healthy women were investigated using a
suprathreshold transcranial magnetic stimulation (TMS) in the
paired-pulse paradigm with long interstimulus intervals (ISI =
20, 60, 120 ms) and measurement of the cortical silent period.
RESULTS: We found no differences for the cortical silent period
and for the long intracortical inhibition between the groups.
Concerning intracortical facilitation, this ability was
significantly more pronounced in patients suffering from
migraine compared with healthy controls. CONCLUSION: Migraineurs
produce an increased intracortical facilitation. The results may
be discussed in line of glutamatergic mechanisms in migraine,
which could be related to altered facilitation.
Publication Types:
PMID: 17371353 [PubMed - indexed for MEDLINE]
J Headache Pain. 2006 Oct;7(5):341-6. Epub 2006 Oct 25. Links
Transcranial
magnetic stimulation for migraine: clinical effects.
Clarke BM, Upton AR, Kamath MV, Al-Harbi T,
Castellanos CM.
Division of Neurology, McMaster University,
Hamilton, Ontario, Canada.
Acta Neurol Belg. 2003
Sep;103(3):144-54.Links
Transcranial
magnetic
stimulation in migraine: a review of facts and controversies.
Fumal A, Bohotin V, Vandenheede M, Schoenen J.
Departments of Neurology and Neuroanatomy, University of
Liège, B-4000 Liège, Belgium.
Med Hypotheses. 2002 Dec;59(6):703-5.
Cellular
telephones
and effects on the brain: the head as an antenna and brain
tissue as a radio receiver.
Weinberger Z, Richter ED.
Jerusalem College of Technology, Jerusalem, Israel.
Headache and other neuropsychological symptoms occur in users of
cellular telephones, and controversy exists concerning risks for
brain cancer. We hypothesize these effects result from the head
serving as an antenna and brain tissue as a radio receiver.
Adv Ther. 2001 May-Jun;18(3):101-9.
Impulse
magnetic-field
therapy for migraine and other headaches: a double-blind,
placebo-controlled study.
Pelka RB, Jaenicke C, Gruenwald J.
Universitat der Bundeswehr Munchen Munich, Germany.
Headache. 1999 Sep;39(8):567-75.
Treatment
of
migraine with pulsing electromagnetic fields: a
double-blind, placebo-controlled study.
Sherman RA, Acosta NM, Robson L.
Orthopedic Surgery Service, Madigan Army Medical Center,
Tacoma, WA 98431, USA.
Headache. 1998 Mar;38(3):208-13.
Initial
exploration
of pulsing electromagnetic fields for treatment of migraine.
Sherman RA, Robson L, Marden LA.
Service of Orthopedic Surgery, Madigan Army Medical Center,
Tacoma, Wash. 98431, USA.
Curr Opin Neurol. 2003 Jun;16(3):327-31.
The electrophysiology of migraine.
Ambrosini A, Schoenen J.
Headache Clinic, INM Neuromed, IRCCS, Pozzilli, Isernia, Italy.
PURPOSE OF REVIEW: The pathophysiology of migraine is far from
being understood. Electrophysiological methods are useful to
investigate peripheral and central mechanisms underlying this
disorder. The purpose of this review is to highlight the results
of electrophysiological studies published during the last year
and to examine their added value to our previous knowledge.
RECENT FINDINGS: Studies by visual and auditory evoked
potentials and event-related responses suggested that lack of
habituation is the principal interictal abnormality of sensory
processing in migraineurs. Recently confirmed for somatosensory
and laser-evoked cortical potentials and for brainstem
responses, it is also responsible for the increased intensity
dependence of auditory evoked potentials. This abnormality is
possibly caused by a reduced cortical preactivation level due to
hypofunctioning subcortico-cortical aminergic pathways. Although
studies of cortical excitability by transcranial magnetic
stimulation have yielded conflicting results, results obtained
using habituation of pattern-reversal visual evoked potentials
to explore cortical excitability changes induced by repetitive
transcranial magnetic stimulation strongly favour the hypothesis
that migraine is characterized by a decreased level of
preactivation excitability. With regard to pain mechanisms in
migraine, electrophysiological studies of trigeminal pathways
using nociceptive blink and corneal reflexes have confirmed that
sensitization of central trigeminal nociceptors occurs during
the attack, and may even persist interictally. SUMMARY:
Scientific publications over the last year confirmed that
electrophysiological methods are particularly suited to
unravelling some of the pathophysiological mechanisms of
migraine. To improve their future contribution, they need to be
better standardized and to be correlated with behavioural,
metabolic and genetic studies.
PMID: 12858069 [PubMed - in process]
------------------------------------------------------------------------
2: Cephalalgia. 2003;23 Suppl
1:13-31. Related Articles, Links
Electrophysiological studies in migraine: a
comprehensive review of their interest and limitations.
Ambrosini A, de Noordhout AM, Sandor PS, Schoenen J.
Headache Clinic, INM Neuromed, IRCCS, Pozzilli (Isernia),Italy.
Electrophysiological methods may help to unravel some of the
pathophysiological mechanisms of migraine. Lack of habituation
is the principal and most reproducible interictal abnormality in
sensory processing in migraineurs. It is found in evoked
potential (EP) studies for every stimulation modality including
nociceptive stimuli, and it is likely to be responsible for the
increased intensity dependence of EP. We have hypothesized that
deficient EP habituation in migraine could be due to a reduced
preactivation level of sensory cortices because of
hypofunctioning subcortico-cortical aminergic pathways. This is
not in keeping with simple hyperexcitability of the cortex,
which has been suggested by some, but not all, studies of
transcranial magnetic stimulation (TMS). A recent study of the
effects of repetitive TMS on visual EP strongly supports the
hypothesis that migraine is characterized by interictal cortical
hypoexcitability. With regard to pain mechanisms in migraine,
electrophysiological studies of trigeminal pathways using
nociceptive blink and corneal reflexes have confirmed that
sensitization of central trigeminal nociceptors occurs during
migraine attacks.
Publication Types:
* Review
* Review, Tutorial
PMID: 12699456 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
3: Clin Neurophysiol. 2003
Jun;114(6):955-72. Related Articles, Links
Evoked potentials and transcranial magnetic
stimulation in migraine: published data and viewpoint on their
pathophysiologic significance.
Schoenen J, Ambrosini A, Sandor PS, Maertens de Noordhout A.
University Department of Neurology, CHR Citadelle, Blvd du
XIIemede Ligne, 1-B-4000, Liege, Belgium.
jean.schoenen@chrcitadelle.be
Migraine is a disorder in which central nervous sytem
dysfunction might play a pivotal role. Electroneurophysiology
seems thus particularly suited to study its pathophysiology. We
have extensively reviewed evoked potential and transcranial
magnetic stimulation studies performed in migraineurs in order
to identify their pathophysiologic significance. Publications
available to us were completed by a Medline search. Retrieved
and personal data were compared with respect to methodology and
interpreted according to present knowledge on cortical
information processing. Results are in part contradictory which
appears to be method-, patient- and disease- related.
Nonetheless, both evoked potential and transcranial magnetic
stimulation studies demonstrate that the cerebral cortex, and
possibly subcortical structures, are dysfunctioning interictally
in both migraine with and without aura. These electrophysiologic
abnormalities tend to normalise just before and during an attack
and some of them seem to have a clear familial and predisposing
character. Besides the studies of magnetophosphenes which have
yielded contrasting results, chiefly because the method is not
sufficiently reliable, most recent electrophysiologic
investigations of cortical activities in migraine favour
deficient habituation and decreased preactivation cortical
excitability as the predominant interictal dysfunctions. We
propose that the former is a consequence of the latter and that
it could favour both interictal cognitive disturbances as well
as a cerebral metabolic disequilibrium that may play a role in
migraine pathogenesis. To summarize, electrophysiologic studies
demonstrate in migraine between attacks a cortical, and possibly
subcortical, dysfunction of which the hallmark is deficient
habituation.
PMID: 12804664 [PubMed - in process]
------------------------------------------------------------------------
4: Curr Opin Neurol. 2002
Jun;15(3):303-9. Related Articles, Links
The electrophysiology of migraine.
Giffin NJ, Kaube H.
Headache Group, Institute of Neurology, Queen Square, London
WC1N 3BG, UK.
Migraine is currently regarded as a neurovascular disorder of
trigeminal sensory processing, generated centrally, probably at
the level of the brainstem. In the past, electrophysiological
techniques have drawn no definite conclusions on either
interictal or ictal changes in migraineurs compared with
controls, largely because of methodological differences.
Recently, two findings have been shown consistently: an
interictal increasing lack of habituation of evoked potentials
with a normalization at the start of the attack and strong
intensity dependence of auditory evoked potentials. These
findings substantiate migraine sufferers as having an abnormal
trait interictally, with the attack characterized by a change in
the state of central processing. Exploitation of these
differences may be a useful tool to study the mechanism of
action of drugs used for the treatment of migraine.
Publication Types:
* Review
* Review, Tutorial
PMID: 12045729 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
5: Cephalalgia. 2000 Oct;20(8):714-9.
Related Articles, Links
Habituation of visual and intensity
dependence of auditory evoked cortical potentials tends to
normalize just before and during the migraine attack.
Judit A, Sandor PS, Schoenen J.
Department of Neurology, Semmelweis University of Medicine,
Budapest, Hungary.
Between attacks, migraine with (MO) or without aura (MA)
patients show deficient habituation of pattern-reversal visual
evoked potentials (PR-VEP) and a strong intensity dependence of
auditory evoked cortical potentials (IDAP). Clinical
observations of migraine prodromes and previously published
electrophysiological studies suggest that cortical information
processing may vary in close temporal relationship to the
attack. We studied PR-VEP and IDAP just before (11 MO pts),
during (23 MO, 3 MA), 1 day following (27 MO, 1 MA) and 2 days
following (14 MO) a migraine attack. The results were compared
with a large group of MO patients recorded at a distance of at
least 3 days from an attack (n = 66 for IDAP; n = 39 for VEP).
Patients recorded the day before the attack had on average an
habituation of -13.6+/-20.5% (mean +/- SD) between the 5th and
1st block of 100 averaged VEP responses and a flat (0.38+/-1.06
microV/10 dB) amplitude-stimulus intensity function (ASF) slope
of the auditory evoked cortical potential. Both values were
significantly different from those obtained in the attack
interval (P=0.003; P=0.020). During the attack, VEP habituation
was less pronounced (-0.17+/-26.2%) and ASF slopes remained flat
(0.32+/-1.44 microV/10 dB; P=0.002 compared to interval). During
the 2 days following the attack, VEP habituation was replaced by
potentiation (+0.09+/-29.1% the 1st day; 19.5+/-45.7% the 2nd
day) and ASF slopes increased markedly (0.87+/-1.39 and
1.14+/-1.12 microV/10 dB). The normalization of evoked cortical
responses just before and during the attack, might reflect an
increase in the cortical preactivation level due to enhanced
activity in raphe-cortical serotonergic pathways.
PMID: 11167900 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
6: Clin Neurosci. 1998;5(1):10-7.
Related Articles, Links
Cortical electrophysiology in migraine and
possible pathogenetic implications.
Schoenen J.
Department of Neurology, University of Liege, CHR Citadelle,
Liege, Belgium. Schoenen.J@innet.be
According to recent evoked potential studies a fundamental,
probably protective, feature of cortical information processing,
i.e., response habituation during stimulus repetition, is
abnormal in migraine between attacks. The deficient habituation
is found for different sensory modalities and experimental
paradigms: pattern-reversal visual evoked potentials (same
stimulus at a constant intensity), cortical auditory evoked
potentials (same stimulus at increasing intensities), and
auditory event-related potential obtained in a passive "oddball"
paradigm (novel stimulus). The abnormal information processing
is an interictal cortical dysfunction most likely due to
inadequate control by the so-called "state-setting,
chemically-addressed pathways" originating in the brain stem, in
particular by the serotonergic pathway, leading to a low
preactivation level of sensory cortices. We propose that it may
play a pivotal role in migraine pathogenesis in conjunction with
the reported decrease of brain mitochondrial energy reserve, by
favouring a rupture of metabolic homeostasis and biochemical
shifts capable of activating the trigeminovascular system and,
thus, of producing a migraine attack. We postulate that both the
deficient habituation in information processing and the deranged
oxygen metabolism may have behavioral correlates. Which of these
abnormalities are inherited, acquired, or both remains to be
determined.
Publication Types:
* Review
* Review, Academic
PMID: 9523052 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
7: Biomed Pharmacother.
1996;50(2):71-8. Related Articles, Links
Deficient habituation of evoked cortical
potentials in migraine: a link between brain biology, behavior
and trigeminovascular activation?
Schoenen J.
Department of Neurology, University of Liege, Belgium.
According to recent evoked potential studies, a fundamental,
probably protective, feature of cortical information processing,
ie, response habituation during stimulus repetition, is abnormal
in migraine between attacks. The deficient habituation is found
for different sensory modalities and experimental paradigms:
pattern-reversal visual evoked potentials (same stimulus at a
constant intensity), cortical auditory evoked potentials (same
stimulus at increasing intensities) and auditory event-related
potentials obtained in a passive "oddball" paradigm (novel
stimulus). The abnormal information processing is an interictal
cortical dysfunction most likely due to inadequate control by
the so-called "state-setting, chemically-addressed pathways"
originating in the brain stem, in particular by the serotonergic
pathway, leading to a low preactivation level of sensory
cortices. We suggest that it may play a pivotal role in migraine
pathogenesis in conjunction with the reported decrease of brain
mitochondrial energy reserve, by favouring a rupture of
metabolic homeostasis and biochemical shifts capable of
activating the trigeminovascular system and thus capable of
producing a migraine attack. We postulate that both the
deficient habituation in information processing and the deranged
oxygen metabolism may have behavioral correlates. Which of these
abnormalities are inherited, acquired or both remains to be
determined.
Publication Types:
* Review
* Review, Tutorial
PMID: 8761712 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
8: Clin Neurophysiol. 2000
Jun;111(6):1124-9. Related Articles, Links
Comparison of visual and auditory evoked
cortical potentials in migraine patients between attacks.
Afra J, Proietti Cecchini A, Sandor PS, Schoenen J.
Department of Neurology Semmelweis University of Medicine,
Budapest, Hungary.
OBJECTIVE: As both habituation of pattern reversal visual evoked
potentials (PR-VEP) (Schoenen J, Wang W, Albert A, Delwaide PJ.
Potentiation instead of habituation characterizes visual evoked
potentials in migraine patients between attacks. Eur J Neurol
1995;2:115-122) and intensity dependence of auditory evoked
cortical potentials (IDAP) (Wang W, Timsit-Berthier M, Schoenen
J. Intensity dependence of auditory evoked potentials in
migraine: an indication of cortical potentiation and low
serotonergic neurotransmission? Neurology 1996;46:1404-1409)
were found abnormal in migraine between attacks, we have
searched for intraindividual correlations between both tests in
59 migraine patients (22 with aura [MA], 37 without aura [MO])
and in 23 healthy volunteers (HV). METHODS: Amplitude change of
the PR-VEP N1-P1 was measured between the 1st and 5th block of
50 sequential averagings during continuous stimulation at 3.1
Hz. IDAP was computed from N1-P2 amplitudes of 100 averagings
during stimulations at 40, 50, 60 and 70 dB SL.
Amplitude-stimulus intensity function (ASF) slopes and amplitude
changes between 40 and 70 dB were calculated. MO and MA differed
from HV in PR-VEP amplitude change (P=0.007) and IDAP slope (P =
0.0004). RESULTS: There was no significant correlation between
VEP amplitude changes and IDAP slopes, nor between the latter
two and attack frequency or disease duration. A negative
correlation was found between the amplitude of the first block
of averaged responses and potentiation of VEP in all subject
groups (P = 0.03) as well as between the amplitude of the
auditory evoked potential, at 40 dB, and the percentage of
amplitude increase between 40 and 70 dB in MO (P = 0.004) and MA
(P = 0.007). ASF slopes and 40 dB amplitudes were significantly
correlated only in the MA group (P = 0.002). These results
confirm the interictal deficit of habituation in cortical
processing of repetitive visual and auditory information in
migraine. Since there is no intraindividual correlation between
the cortical responses to these sensory modalities they are
complementary tools for the study of migraine and may help to
identify subgroups of patients with distinct pathophysiological
mechanisms. CONCLUSIONS: The strong negative correlation between
the initial amplitude of evoked potentials and their amplitude
increase during subsequent averaging confirms that the response
potentiation in migraine is likely to be due to a reduced
preactivation level of sensory cortices.
PMID: 10825720 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
9: Brain. 2002 Apr;125(Pt 4):912-22.
Related Articles, Links
Effects of repetitive transcranial magnetic
stimulation on visual evoked potentials in migraine.
Bohotin V, Fumal A, Vandenheede M, Gerard P, Bohotin C, Maertens
de Noordhout A, Schoenen J.
Department of Neurology, University of Liege, Liege, Belgium.
Between attacks, migraine patients are characterized by
potentiation instead of habituation of stimulation-evoked
cortical responses. It is debated whether this is due to
increased or decreased cortical excitability. We have studied
the changes in visual cortex excitability by recording
pattern-reversal visual evoked potentials (PR-VEP) after low-
and high-frequency repetitive transcranial magnetic stimulation
(rTMS), known respectively for their inhibitory and excitatory
effect on the cortex. In 30 patients (20 migraine without, 10
with aura) and 24 healthy volunteers, rTMS of the occipital
cortex was performed with a focal figure-of-eight magnetic coil
(Magstim). Nine hundred pulses were delivered randomly at 1 or
10 Hz in two separate sessions. Stimulus intensity was set to
the phosphene threshold or to 110% of the motor threshold if no
phosphenes were elicited. Before and after rTMS, PR-VEP were
averaged sequentially in six blocks of 100zztieresponses during
uninterrupted 3.1 Hz stimulation. In healthy volunteers, PR-VEP
amplitude was significantly decreased in the first block after 1
Hz rTMS and the habituation normally found in successive blocks
after sustained stimulation was significantly attenuated. In
migraine patients, 10 Hz rTMS was followed by a significant
increase of first block PR-VEP amplitude and by a reversal to
normal habituation of the potentiation (or dishabituation)
characteristic of the disorder. This effect was similar in both
forms of migraine and lasted for at least 9 min. There were no
significant changes of PR-VEP amplitudes after 1 Hz rTMS in
migraineurs and after 10 Hz rTMS in healthy volunteers, nor
after sham stimulation. The recovery of a normal PR-VEP
habituation pattern after high-frequency rTMS is probably due to
activation of the visual cortex and the dishabituation in
healthy volunteers to cortical inhibition. We conclude,
therefore, that the deficient interictal PR-VEP habituation in
migraine is due to a reduced, and not to an increased,
pre-activation excitability level of the visual cortex.
PMID: 11912123 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
10: Brain. 2003 Jun 23 [Epub ahead of
print]. Related Articles, Links
Lack of habituation causes high intensity
dependence of auditory evoked cortical potentials in migraine.
Ambrosini A, Rossi P, De Pasqua V, Pierelli F, Schoenen J.
Headache Clinic, INM Neuromed, Pozzilli (Isernia), Italy.
Migraineurs are characterized interictally by lack of
habituation, or even potentiation, of cortical evoked potentials
during repetitive stimulation and by a strong intensity
dependence of auditory evoked potentials (IDAP). To determine
whether these two features of sensory processing are
interrelated, we have studied them simultaneously on the same
recordings of auditory evoked potentials (AEPs). AEPs were
obtained at four different stimulation intensities in 14
patients suffering from migraine without aura (MO) and 14
healthy volunteers (HV). For each intensity, 120 trials were
averaged off-line globally and over four sequential blocks of 30
trials. IDAP was expressed by the amplitude/stimulus intensity
function (ASF slope) for global and block averages. Habituation
was calculated as the percentage amplitude variation between the
first and fourth blocks for each stimulus intensity. The IDAP
slope for global averages was higher in MO (1.05 +/- 0.27 micro
V/10 dB) than in HV (0.64 +/- 0.45 micro V/10 dB) (P = 0.008),
but IDAP slopes for block averages were greater in MO only at
the fourth block (P = 0.048). First block amplitudes tended to
be lower in MO, except at 80 dB. There was a potentiation of AEP
amplitudes at every stimulus intensity in MO, contrasting with
habituation in HV. IDAP slopes were negatively correlated with
mean habituation percentages in pooled data from patients and
controls (r = -0.610; P = 0.0006). This study confirms that IDAP
is higher in migraineurs than in healthy controls. It also shows
that the AEP habituation is replaced by potentiation at all
stimulus intensities. The negative correlation found between
IDAP and habituation suggests that the latter is able to have a
strong influence on the former and perhaps even lead to it. In
migraine, the habituation deficit amplifies the IDAP and may
thus be the causal functional abnormality. We propose that it is
due to a decreased pre-activation level of sensory cortices, a
hypothesis also supported in this study by the lower amplitude
of first AEP blocks in patients.
PMID: 12821515 [PubMed - as supplied by publisher]
------------------------------------------------------------------------
11: Neurosci Lett. 2001 Jun
22;306(1-2):132-4. Related Articles, Links
Reduced gating of middle-latency auditory
evoked potentials (P50) in migraine patients: another indication
of abnormal sensory processing?
Ambrosini A, De Pasqua V, Afra J, Sandor PS, Schoenen J.
Headache Clinics - IRCCS Neuromed via Atinense, 18, I-86077 ,
Pozzilli (Isernia), Italy.
Habituation of cortical evoked responses to repetitive stimuli
is reduced in migraine between attacks. To explore another
aspect of information processing, we measured auditory sensory
gating. The amplitude of the P50 response to the second of two
homologous stimuli was significantly less reduced in migraineurs
than in healthy volunteers. This lack of auditory sensory gating
may be due to a hypofunction of monoaminergic
subcortico-cortical pathways, which is also supposed to cause
the interictal deficit of cortical habituation to repetitive
stimuli.
PMID: 11403975 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
12: Neurology. 1996 May;46(5):1404-9.
Related Articles, Links
Intensity dependence of auditory evoked
potentials is pronounced in migraine: an indication of cortical
potentiation and low serotonergic neurotransmission?
Wang W, Timsit-Berthier M, Schoenen J.
Department of Neurology, University of Liege, Belgium.
Migraine is associated with stimulus hypersensitivity, increased
evoked cortical responses, and abnormal 5-HT levels in
peripheral blood. We studied cortical auditory evoked potentials
(AEPs) between attacks in 35 patients suffering from migraine
without aura (MO, n = 25) or with aura (MA, n = 10) and in 25
healthy volunteers. Binaural tones were delivered at 40, 50, 60,
and 70 dB sensation level (SL) in a pseudorandomized order. The
intensity dependence of the auditory N1-P2 component was
significantly greater in MO (p = 0.003) and MA (p = 0.02)
patients than in healthy controls, resulting in a much steeper
amplitude/stimulus intensity function slope. When three
sequential blocks of 40 averaged responses were analyzed at the
40- and 70-dB SL intensities, N1-P2 amplitude decreased in
second and third blocks at both intensities in controls, but
increased in migraineurs, a difference that was significant in
both blocks for the 70-dB SL stimulus. The strong interictal
dependence of AEPs on stimulus intensity may thus be due to
potentiation (instead of habituation) of the response during
repetition of the high-intensity stimulation. In concordance
with previous studies of visual evoked potentials, these results
confirm that migraine is characterized between attacks by an
abnormality of cortical information processing, which might be a
consequence of low 5-HT transmission and favor cortical energy
demands.
PMID: 8628490 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
13: Cephalalgia. 2000
Nov;20(9):804-20. Related Articles, Links
Visual, long-latency auditory and brainstem
auditory evoked potentials in migraine: relation to pattern
size, stimulus intensity, sound and light discomfort thresholds
and pre-attack state.
Sand T, Vingen JV.
Department of Clinical Neurosciences, Trondheim University
Hospital, Norwegian University of Science and Technology.
trond.sand@medisin.ntnu.no
We aimed to estimate primary sensory evoked potential (EP)
amplitude, amplitude-intensity functions and habituation in
migraine patients compared with healthy control subjects and to
investigate the possible relation to check size, sound and light
discomfort thresholds, and the time to the next attack.
Amplitudes of cortical visual evoked potentials (VEP, check size
8' and 33'), cortical long latency auditory evoked potential
(AEP NIP1; 40, 55 and 70 dB SL tones) and brainstem auditory
evoked potential (BAEP wave IV-V; 40, 55 and 65 dB SL clicks)
were recorded and analysed in a blind and balanced design. The
difference between the response to the first and the second half
of the stimulus sequence was used as a measure of habituation.
Twenty-one migraine patients (16 women and five men, mean age
39.3 years, six with aura, 15 without aura) and 22 sex- and
age-matched healthy control subjects were studied (18 women and
four men, mean age 39.5 years). Low sound discomfort threshold
correlated significantly with low levels of BAEP wave IV-V
amplitude habituation (r = -0.30, P = 0.05). VEP an AEP
amplitudes, habituation, and amplitude-intensity function (ASF)
slopes did not differ between groups when ANOVA main factors
were considered. Control group VEP habituation was found for
small check stimuli (P = 0.04), while potentiation was observed
for medium sized checks (P = 0.02). The eight migraine patients
who experienced headache within 24 h after the test tended to
have increased BAEP wave IV-V ASF slopes (P = 0.08). This
subgroup did also have a significant VEP habituation to small
checks (P = 0.04). No correlation was found between different
modalities. These results suggest that: (i) VEP
habituation/potentiation state and brainstem activatio state may
depend on the attack-interval cycle in migraine; (ii) VEP
habituation/ potentiation may depend on spatial stimulus
frequency; (iii) phonophobia (and possibly photophobia) may
depend more on subcortical (brainstem) function than on cortical
mechanisms; (iv) low cortical preactivation in migraine could
not be confirmed; (v) EP habituation and ASF analysis may
reflect sensory modality-specific, not generalized, central
nervous system states in migraine and healthy control subjects.
PMID: 11167910 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
14: Headache. 2000 Jan;40(1):30-5.
Related Articles, Links
Prophylactic treatment of migraine with
beta-blockers and riboflavin: differential effects on the
intensity dependence of auditory evoked cortical potentials.
Sandor PS, Afra J, Ambrosini A, Schoenen J.
Neurology Department, CHR Citadelle, University of Liege,
Belgium.
OBJECTIVE: To investigate the influence of different
pharmacological treatments on the intensity dependence of
auditory evoked cortical potentials in migraineurs. BACKGROUND:
Between attacks, patients with migraine show abnormalities in
cortical information processing and decreased brain
mitochondrial energy reserve. Both are most probably relevant
for migraine pathogenesis, and they could be differentially
modified by prophylactic drug therapy. Design.-The intensity
dependence of the auditory evoked cortical potentials is, on
average, increased in migraine. We have studied this intensity
dependence in 26 patients before and after a 4-month period of
prophylaxis with beta-blockers (n = 11, all migraine without
aura; metoprolol or bisoprolol) or riboflavin (n = 15, migraine
without aura: 13, migraine with aura: 2). Recordings were
performed at least 3 days before or after an attack. RESULTS:
After the treatment with beta-blockers, the intensity dependence
of the auditory evoked cortical potentials was significantly
decreased (before: 1.66+/-1.02 microV/10 dB; after: 0.79+/-1.06
microV/10 dB, P=.02). The decrease in intensity dependence was
correlated significantly with clinical improvement (r = .69, P =
.02). There was no change in intensity dependence after
riboflavin treatment (before: 1.80+/-0.81 microV/10 dB; after:
1.56+/-0.83 microV/10 dB, P = .39), although the majority of
patients showed improvement. CONCLUSIONS: These results confirm
that beta-blockers and riboflavin act on two distinct
pathophysiological mechanisms. Combining both treatments might
enhance their efficacy without increasing central nervous system
side effects.
PMID: 10759900 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
15: Eur J Neurol. 2002
May;9(3):227-32. Related Articles, Links
Median nerve somatosensory evoked
potentials in migraine.
Ozkul Y, Uckardes A.
Department of Neurology, Faculty of Medicine, University of
Harran, Sanliurfa, Turkey. yasarozkul@yahoo.com
In visual evoked potential studies, habituation during stimulus
repetition with the same stimulus at a constant intensity has
been found to be abnormal in migraineurs between attacks. The
purpose of this study was to investigate habituation of
somatosensory evoked potentials (SEPs) and the effects of
migraine on them. Eighty-five subjects were included in the
study: 30 healthy volunteers (HVs) and 55 migraineurs [30 with
migraine without aura (MO), 25 with migraine with aura (MA)].
During continuous stimulation at 3 Hz, four blocks of 100
responses were sequentially averaged of Erb's point (N9),
cervical (N13), and cortical (N20) median nerve SEPs. Mean
amplitude changes in the second, third and fourth blocks are
expressed as percentages of the first block. There was
habituation to N13 and N20 in the second, third and fourth
blocks in HVs. In the migraine groups, there was no habituation;
on the contrary, potentiation was found. This potentiation was
statistically significant only in the second blocks for N13 (MO
P=0.007, MA P=0.01 versus HVs). However, in both migraineur
groups, the rate of N20 potentiations was statistically
significant versus that in HVs for all blocks (all P < 0.05).
It is concluded that whilst physiological habituation occurs in
HVs for cervical and cortical SEPs, in migraine patients there
is an interictal deficit of habituation of this sensory
modality.
PMID: 11985630 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
16: Neuroreport. 1999 Apr
26;10(6):1235-8. Related Articles, Links
Familial influences on cortical evoked
potentials in migraine.
Sandor PS, Afra J, Proietti-Cecchini A, Albert A, Schoenen J.
Neurology Department, University of Zurich, Switzerland.
Cortical information processing in migraine patients is impaired
between attacks, showing deficient habituation of
pattern-reversal visual evoked potentials (VEP), and strong
intensity dependence of auditory cortical evoked potentials
(IDAP). This could be a genetic trait as certain genetic
patterns are known for evoked potentials in healthy subjects. We
investigated VEP habituation and IDAP in 20 pairs of migraineurs
made up of parents and their children. Using a Monte-Carlo
statistical method, we selectively assessed vertical familial
influences. VEP habituation and IDAP were abnormal in both
parents and children. However, similarity was far more
pronounced between related pairs than between unrelated pairs.
Familial influences are highly significant in determinants of
cortical information processing in migraineurs, hence supporting
the important role of genetic factors.
PMID: 10363931 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
17: Headache. 2000 Jan;40(1):36-40.
Related Articles, Links
Influence of colors on habituation of
visual evoked potentials in patients with migraine with aura and
in healthy volunteers.
Afra J, Ambrosini A, Genicot R, Albert A, Schoenen J.
Department of Neurology, Semmelweis University of Medicine,
Budapest, Hungary.
OBJECTIVE: To investigate whether colored glasses influence the
habituation of visual evoked potentials. BACKGROUND: We have
previously shown that during pattern-reversal stimulations
lasting 2 minutes the amplitude of the visual evoked potential
increases in migraine with and without aura between attacks,
whereas it decreases in healthy volunteers. Red light was found
to increase visually evoked EEG fast activity only in children
with migraine with aura. Wearing rose-tinted glasses for 4
months decreased attack frequency in parallel with a reduction
of the visually evoked EEG fast activity. METHODS: We compared
the change in amplitude of the visual evoked potential using
five different tinted glasses in 12 patients with migraine with
aura and in 10 healthy volunteers. During continuous stimulation
at 3.1 Hz, five blocks of 50 responses were sequentially
averaged using red, yellow, green, blue, and grey glasses and
without glasses in a random order and analyzed in terms of
latencies and N1-P1 amplitudes. Amplitude changes were
calculated for each block by comparison with the first block in
every condition and analyzed statistically using Zerbe's method.
RESULTS: In healthy volunteers, the visual evoked potential
amplitude increased with red glasses compared to without glasses
(P = .05) or with green glasses (P = .03). In patients with
migraine with aura, no significant difference was detected using
colored glasses. Our findings in healthy volunteers are in line
with earlier reports of increased excitability of the human
visual cortex when exposed to red light. The lack of such a
pattern in patients with migraine with aura suggests that the
visual cortex is interictally hypoexcitable rather than
hyperexcitable, which is consistent with studies of transcranial
magnetic stimulation.
PMID: 10759901 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
18: Headache. 2002
Jul-Aug;42(7):582-7. Related Articles, Links
Effects of fluoxetine on habituation of
pattern reversal visually evoked potentials in migraine
prophylaxis.
Ozkul Y, Bozlar S.
University of Harran, Faculty of Medicine, Department of
Neurology, Sanliurfa, Turkey.
OBJECTIVE: To investigate the effects of fluoxetine in migraine
prophylaxis on habituation of visually evoked potentials.
BACKGROUND: Habituation of pattern reversal visually evoked
potentials was found to be abnormal in migraine between attack,
and this abnormality was most likely due to serotonergic pathway
dysfunction in the brain stem. METHODS: One hundred nineteen
subjects were included in the study: 40 healthy volunteers and
79 migraineurs not taking any prophylactic migraine medication
(44 without aura and 35 with aura). Visually evoked potentials
in migraineurs were recorded in the headache-free interval.
Amplitude change of the visually evoked potentials (N1-P1) was
measured between the first and fifth block of 50 sequential
averagings during continuous stimulation at 3.1 Hz. All
migraineurs were placed on fluoxetine 20 mg/day for prophylaxis
of migraine. One month later, visually evoked potentials were
recorded again. RESULTS: Mean amplitude changes in the fifth
block expressed as percentages of the first block were -13.4%
+/- 19.2% in healthy volunteers, 9.8% +/- 23.3% in migraine
without aura, and 4.4% +/- 8.7% in migraine with aura during the
baseline period. The difference was significant between
migraineurs and healthy volunteers (both P= 0.0001), but not
between migraineur groups. After treatment, amplitude changes
were -9.3% +/- 14.5% in migraine without aura and -10.1% +/-
11.5% in migraine with aura. Habituation pattern tended to
normalize with prophylactic treatment, and mean amplitude
changes were not significant between migraineurs and healthy
volunteers (both P = 0.4). CONCLUSIONS: We concluded that the
fluoxetine prophylaxis corrects the interictal deficit of
habituation in migraineurs.
Publication Types:
* Clinical Trial
* Controlled Clinical Trial
PMID: 12482209 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
19: Brain. 1998 Feb;121 ( Pt
2):233-41. Related Articles, Links
Visual evoked potentials during long
periods of pattern-reversal stimulation in migraine.
Afra J, Cecchini AP, De Pasqua V, Albert A, Schoenen J.
Department of Neurology, University of Liege, Belgium.
We have previously shown that during repetitive pattern-reversal
stimulation, lasting 2 min, the amplitude of the visual evoked
potential (PR-VEP) increases in migraineurs when tested
interictally whereas it decreases in healthy control subjects.
According to Sappey-Marinier et al. (J Cereb Blood Flow Metab
1992; 12: 584-92) habituation of the PR-VEP in normal subjects
is maxima after 12 min, at a time when there is a decrease of
stimulation-enhanced lactate levels in the occipital cortex. We
have therefore compared PR-VEP during long periods of repetitive
stimulation in healthy control subjects (n = 25) and in patients
suffering from migraine without (n = 25) and with aura (n = 15)
between attacks. During uninterrupted stimulation at 3.1 Hz VEPs
were sequentially averaged in blocks of 100 responses for a
total duration of 15 min and analysed in terms of latencies and
peak-to-peak amplitudes of N1-P1 and P1-N2 peaks. Amplitude
changes from the baseline were calculated for each block, by
comparison with the first block, and analysed statistically
using Zerbe's method. The N1-P1 and P1-N2 amplitudes in the
first block tended to be lower in migraineurs than in healthy
control subjects. During the 15 min of stimulation, amplitudes
of both components progressively decreased in control subjects,
but remained stable in both groups of patients. The difference
between patients and control subjects proved to be significant
(P < 0.05). The neurophysiological data were not correlated
with clinical features such as attack frequency or duration of
illness. These results are yet another demonstration in migraine
of an interictal habituation deficit in cortical information
processing, which might favour lactate accumulation in sensory
cortices during sustained activation.
PMID: 9549502 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
20: Cephalalgia. 2002
Feb;22(1):48-53. Related Articles, Links
A neural network model of sensitization of
evoked cortical responses in migraine.
Thomas E, Sandor PS, Ambrosini A, Schoenen J.
Research Center for Cellular and Molecular Neurobiology,
University of Liege, Belgium. ethomas@ulg.ac.be
Migraine patients show abnormalities of cerebral
electrophysiology that manifest themselves mainly during the
attack interval. Cortical-evoked potentials of migraineurs fail
to habituate to repetitive presentations of visual stimuli, and
the amplitude of components of their auditory cortical-evoked
potentials have a higher dependence on the stimulus intensities
than in healthy subjects. A computer model of a neural hetwork
has been developed that is able to reproduce both these
neurophysiological dysfunctions. It predicts a positive
correlation between the magnitudes of both these dysfunctions.
The model also offers an explanation of why mutations in the
same ion channel gene with opposite consequences on channel
function, e.g. P/Q Ca2+ channels in migraine, may lead to
similar electrophysiological abnormalities.
PMID: 11993613 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
21: Funct Neurol. 2000;15 Suppl
3:68-72. Related Articles, Links
From neurophysiology to genetics: cortical
information processing in migraine underlies familial
influences--a novel approach.
Sandor PS, Afra J, Proietti Cecchini AP, Albert A, Schoenen J.
Department of Neurology, CHR Citadelle, University of Liege,
Belgium.
Migraine patients show impaired cortical information processing
between attacks with deficient habituation of pattern-reversal
visual evoked potentials (VEP), and strong intensity dependence
of auditory cortical evoked potentials (IDAP). This could be a
genetic trait as certain genetic patterns are known for evoked
potentials in healthy subjects. VEP-habituation and IDAP were
studied in 40 migraine patients, i.e. pairs of 20 parents and
their children. We developed a novel approach based on Monte
Carlo statistics to selectively assess vertical familial
influences. Both groups, parents and children, were
characterized by abnormal VEP-habituation and IDAP. However,
similarity between related pairs was far more pronounced than
similarity between unrelated pairs. Assessed with a novel
statistical approach, familial influences proved to be highly
significant in determining cortical information processing in
migraineurs, thus supporting the important role of genetic
factors.
Publication Types:
* Clinical Trial
* Randomized Controlled Trial
PMID: 11200803 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
22: Cephalalgia. 1998 Jun;18(5):261-5;
discussion 241. Related Articles, Links
Interictal potentiation of passive
"oddball" auditory event-related potentials in migraine.
Wang W, Schoenen J.
Department of Neurology, University of Liege, Belgium.
We have studied habituation of the P3a component of the passive
"oddball" auditory event-related potential which reflects
automatic processing of a "novel" stimulus in 24 patients
suffering from migraine without aura and in 21 healthy
volunteers. Three blocks of responses to 160 standard and to 40
novel tones were sequentially averaged at Cz and analyzed for
latencies and peak-to-peak amplitudes. Latencies of components
N1 and P2 elicited by standard tones and of components N1, P2,
N2, and P3a elicited by novel tones were not significantly
different between sequential blocks or between subject groups,
nor were mean N1-P2 amplitudes. The N2-P3a amplitude tended to
be lower in migraine, but not significantly so. The most
striking result in migraineurs was a significant potentiation of
N2-P3a in successive blocks, contrasting with an habituation in
controls. Our previous evoked- and event-related potential
studies and the present one suggest that deficient habituation,
or even potentiation, represents interictally a fundamental
dysfunction of cortical information processing in migraine,
which might increase energy demands and play a role in
etiopathogenesis.
PMID: 9673805 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
23: Rev Neurol (Paris). 2001
Apr;157(4):365-75. Related Articles, Links
[Clinical and pathophysiological
contribution of event-related potentials used to study migraine
headache]
[Article in French]
Legrain V, Janne P, Laloux P, Ossemann M, Dupuis M, Reynaert C.
Departement de psychologie clinique, Faculte de Psychologie et
des Sciences de l'Education, Universite Catholique de Louvain,
Louvain-la-Neuve. legrain@clap.ucl.ac.be
Event-related potentials are electric brain manifestations
evoked by mental activities. This neurophysiological technique
is able to describe temporal succession of cognitive processing
and allows to measure the neurobiological correlates of each
cognitive activity. The evoked potentials of the oddball
paradigm and the Contingent Negative Variation (CNV) are also
concerned by clinical applications in neuropsychiatry, in
neurology and in psychopharmacology. In the case of migraine,
the studies with CNV recorded between migraine attacks are
characterized by two major phenomena, cerebral hyperreactivity
and lack of habituation to repetitive stimuli. From cognitive
point of view, this can be interpreted as a difficulty from
migraine sufferers to adapt their information-processing to
environmental constraints. From neurological point of view, this
trouble is related with dysregulation of norepinephrin and
serotonin ascending pathways. Studies with the oddball paradigm
potentials remain non consistent. The mismatch between different
methodologies could explain such a lack of consistency. The
neurophysiological studies have contributed to new
physiopathological hypothesis of migraine. Those hypothesis
reveal that a shift in the brain metabolic homeostasis could be
the common factor of migraine attacks. The clinical contribution
of event-related potentials is of little use in the diagnosis of
migraine. But two purposes have been suggested: the differential
diagnosis between common migraine and tension-type headaches and
the monitoring of beta-blocking agents prophylaxis.
Publication Types:
* Review
* Review, Academic
PMID: 11398007 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
24: Cephalalgia. 2000
Sep;20(7):621-31. Related Articles, Links
Olfactory and trigeminal event-related
potentials in migraine.
Grosser K, Oelkers R, Hummel T, Geisslinger G, Brune K, Kobal G,
Lotsch J.
Department of Experimental and Clinical Pharmacology and
Toxicology, University of Erlangen Nurnberg, Erlangen, Germany.
BACKGROUND: Trigeminal/neuronal hyperexcitability and spreading
depression activating the trigemino-vascular system are
discussed in migraine-pathophysiology. This study investigated
trigeminal and olfactory event-related potentials in
migraineurs. METHODS: Nasal chemosensitivity was assessed in 19
female migraineurs with or without aura > 72 h before or
after an attack and in 19 healthy females employing
event-related cortical potentials (ERPs) after specific
trigeminal stimulation of nasal nociceptors with short pulses of
CO2, and specific olfactory stimulation with H2S. Odour
thresholds and odour identification performance were also
tested. RESULTS: Migraineurs exhibited greater responses to
trigeminal stimulation, indicated by significantly larger ERP
amplitudes N1. In contrast, olfactory ERP amplitudes P1N1 were
significantly smaller in migraineurs. A leave-one-out
classification procedure on the basis of these two parameters
assigned 76.3% cases correctly. The olfactory ERP amplitude
discriminated better between groups than trigeminal ERPs (71.1
vs. 68.4% correct classification). CONCLUSIONS: Our data suggest
trigeminal hyperexcitability in migraineurs. A general increase
of nasal chemosensitivity is not supported because of smaller
olfactory ERP amplitudes in migraineurs. Olfactory ERPs
discriminate better than trigeminal ERPs between migraineurs and
controls, emphasizing the significance of the olfactory system
in migraine.
PMID: 11128819 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
25: Brain. 1999 Jun;122 ( Pt
6):1147-55. Related Articles, Links
Visual evoked potentials in migraine
patients: alterations depend on pattern spatial frequency.
Oelkers R, Grosser K, Lang E, Geisslinger G, Kobal G, Brune K,
Lotsch J.
Department of Experimental and Clinical Pharmacology, University
of Erlangen-Nurnberg, Germany.
rieke_oelkers@med.uni-heidelberg.de
Visual information is conducted by two parallel pathways
(luminance- and contour-processing pathways) which are thought
to be differentially affected in migraine and can be
investigated by means of pattern-reversal visual evoked
potentials (VEPs). Components and habituation of VEPs at four
spatial frequencies were compared between 26 migraineurs (13
without aura, MO; 13 with aura, MA) and 28 healthy volunteers.
Migraineurs were recorded in the headache-free interval (at
least 72 h before and after an attack). Five blocks of 50
responses to chequerboards of 0.5, 1, 2 and 4 cycles per degree
(c.p.d.) were sequentially averaged and analysed for latency and
amplitude. Differences in VEPs were dependent on spatial
frequency. Only when small checks were presented, i.e. at high
spatial frequency (2 and 4 c.p.d.), was the latency of N2
significantly prolonged in MA and did it tend to be delayed in
MO subjects. Habituation behaviour was not significantly
different between groups under the stimulating conditions
employed. Prolonged N2 latency might be explained by the lack or
attenuation of a contour-specific component N130 in migraineurs,
indicating an imbalance of the two visual pathways with relative
predominance of the luminance-processing Y system. These results
reflect an interictally persisting dysfunction of precortical
visual processing which might be relevant in the pathophysiology
of migraine.
PMID: 10356066 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
26: Exp Brain Res. 2002 Jul;145(2):177-81.
Epub 2002 May 09. Related Articles, Links
Modulation of visual cortical excitability
in migraine with aura: effects of 1 Hz repetitive transcranial
magnetic stimulation.
Brighina F, Piazza A, Daniele O, Fierro B.
Istituto di Neuropsichiatria, Universita di Palermo, via G. La
Loggia 1, 90129 Palermo, Italy.
Recent studies showed hyperexcitability of the occipital cortex
in subjects affected by migraine with aura. It has been shown
that 1 Hz repetitive transcranial magnetic stimulation (rTMS)
reduces excitability of visual cortex in normal subjects. The
aim of the study was to investigate the effects of low frequency
(1 Hz) rTMS on visual cortical excitability by measuring changes
in phosphene threshold (PT) in subjects with migraine with aura.
Thirteen patients with migraine with aura and 15 healthy
controls were examined. Using a standardized transcranial
magnetic stimulation protocol of the occipital cortex, we
assessed the PT (the lowest magnetic stimulation intensity at
which subjects just perceived phosphenes) before and after a
1-Hz rTMS train delivered at PT intensity for 15 min. The
difference in the proportion of subjects reporting phosphenes in
migrainer and control groups was significant (migrainers: 100%
vs controls 47%; P<0.05), and 1 Hz rTMS over the occipital
cortex led to a significantly increased visual cortex
excitability expressed as a decrease in PT in subjects affected
by migraine with aura. Conversely, after a 1-Hz TMS train normal
subjects showed increased PT values, which suggests a decreased
visual cortex excitability. Our findings confirm that the visual
cortex is hyperexcitable in migrainers and suggest a failure of
inhibitory circuits, which are unable to be upregulated by low
frequency rTMS.
PMID: 12110957 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
27: Patol Fiziol Eksp Ter. 1996
Apr-Jun;(2):3-6. Related Articles, Links
[Multimodal evoked potentials and central
mechanisms of afferentation in trigeminal neuralgia]
[Article in Russian]
Meizerov EE, Reshetniak VK, Koroleva MV, Grachev IuV.
Multimodal evoked potentials in patients with trigeminal
neuralgia are analyzed in the paper. The comprehensive studies
of cortical trigeminal somatosensory evoked potentials, visual
evoked potentials, and brainstem auditory evoked potentials have
revealed their changes that are indicative of the impaired
central mechanisms of afferentation in patients with trigeminal
abnormality. The findings are discussed in the light of the
theory of generator mechanisms of neuropathological pain
syndromes.
PMID: 8754133 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
28: J Neurol Sci. 1996
Jul;139(1):106-10. Related Articles, Links
Interictal cortical hyperexcitability in
migraine patients demonstrated with transcranial magnetic
stimulation.
van der Kamp W, Maassen VanDenBrink A, Ferrari MD, van Dijk JG.
Department of Neurology and Clinical Neurophysiology, University
Hospital Leiden, Netherlands.
Cortical excitability to magnetic stimulation was investigated
interictally in 10 patients with migraine with aura, 10 with
migraine without aura and in 10 healthy volunteers. Thresholds,
latencies and amplitudes of the magnetic-evoked potentials
(MEPs) were measured from threshold to 100% stimulus intensity
in 10% steps. Compound motor action potentials (CMAPs) evoked
with supramaximal electrical stimulation of the ulnar nerve were
used to calculate MEP/CMAP amplitude ratios. Thresholds and
latencies of MEPs did not differ between patients and controls.
MEP/CMAP amplitude ratios were significantly increased at all
intensities in patients with migraine with aura (RM-ANOVA, p
< 0.01) and without aura (p < 0.05) compared with
controls. In migraine patients, MEP amplitudes and MEP/CMAP
amplitude ratios were positively related to the frequency of
migraine attacks (Spearman's r = 0.47, p < 0.01 and r = 0.56,
p < 0.002, respectively). MEP parameters were not related to
the side of the headache nor the aura, in either type of
migraine, implying that both hemispheres are equally involved in
migraine. Migraine with aura and, to a lesser extent, migraine
without aura, are associated with increased interictal cortical
excitability.
PMID: 8836980 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
29: Cephalalgia. 1985 May;5 Suppl
2:53-8. Related Articles, Links
Visual evoked potentials and brainstem
auditory evoked potentials in migraine and transient ischemic
attacks.
Benna P, Bianco C, Costa P, Piazza D, Bergamasco B.
A study of brainstem auditory evoked potentials (BAEPs) and
pattern reversal visual evoked potentials (VEPs), recorded in
intercritical phase, was carried out in 20 subjects (10
suffering from common migraine and 10 suffering from
vertebrobasilar TIA) in order to obtain a comparative evaluation
of cortical-subcortical functions. The data we obtained
demonstrate the presence of BAEPs alterations in patients with
previous vertebrobasilar TIA: no abnormalities were found in the
migraine group. VEPs parameters are normal in both groups. Our
data show that the study of the so-called "stimulus-related"
potentials, such as BAEPs and pattern reversal VEPs, is useful
in evaluating the damage produced by any noxa, while it cannot
clearly emphasize individual factors predisposing to a specific
pathology, as the absence of specific alterations in migraine
patients demonstrates.
PMID: 4016942 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
30: Ann Neurol. 1998
Aug;44(2):209-15. Related Articles, Links
Comment in:
* Ann Neurol. 1999 Mar;45(3):415-6.
* Ann Neurol. 1999 Mar;45(3):416-7.
Interictal cortical excitability in
migraine: a study using transcranial magnetic stimulation of
motor and visual cortices.
Afra J, Mascia A, Gerard P, Maertens de Noordhout A, Schoenen J.
Department of Neurology, CHR Citadelle, University of Liege,
Belgium.
We performed transcranial magnetic stimulations of the motor and
visual cortices in healthy controls (n = 27) and in patients
suffering from migraine without (n = 33) or with (n = 25) aura
between attacks. By using a 13-cm circular coil placed over the
vertex and recordings of the first dorsal interosseus muscle, we
measured thresholds (at rest and during contraction), amplitudes
of motor evoked potentials and cortical silent periods. Paired
stimulations with short (1-20 msec) interstimulus intervals were
performed to assess intracortical inhibition. The visual cortex
was stimulated with the same coil placed over the occipital
scalp (7 cm above the inion) and the prevalence and threshold of
phosphene production was determined. In patients with migraine
with aura, motor thresholds during isometric contraction were
significantly higher, whereas the prevalence of
stimulation-induced phosphene production was lower compared with
healthy controls. These changes were not correlated with attack
frequency or disease duration. No differences were found between
subject groups in thresholds at rest, motor evoked potential
amplitudes, cortical silent periods, or response curves after
paired stimuli. These results are in favor of cortical
hypoexcitability rather than hyperexcitability in patients with
migraine with aura between attacks.
Publication Types:
* Clinical Trial
* Controlled Clinical Trial
PMID: 9708543 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
31: Neurology. 2002 Apr
9;58(7):1066-9. Related Articles, Links
Transcranial magnetic stimulation of visual
area V5 in migraine.
Battelli L, Black KR, Wray SH.
Department of Psychology, Harvard University, Cambridge, MA
02138, USA. Battelli@wjh.harvard.edu
OBJECTIVE: To examine visual cortical excitability in persons
with migraine using transcranial magnetic stimulation (TMS) over
an extrastriate area of the brain, area V5. BACKGROUND: Previous
studies found that persons with migraine have a lower phosphene
threshold than healthy control subjects with TMS delivered over
the primary visual cortical area V1. The result suggests that
the occipital cortex in migraineurs between migraine attacks is
hyperexcitable. However, it is not known whether interictal
cortical hyperexcitability is also present in areas of the
association visual cortex. METHOD: To investigate this,
single-pulse TMS was delivered over visual area V5, the motion
cortex, to 16 persons with migraine and visual aura, nine
migraineurs without visual aura, and 16 healthy control
subjects. TMS was delivered at intensities ranging from 30 to
100% of maximum stimulator output or until the participant
reported seeing phosphenes (visual illusions characterized by
flashes of light). Thresholds to phosphenes were obtained for
each participant using a staircase procedure. RESULT:
Significantly lower phosphene thresholds for TMS delivered over
V5 were found in migraineurs as compared with control subjects.
Qualitatively, the migraineurs' experience of phosphenes were
more vivid, florid, and sustained compared with that of control
subjects. CONCLUSION: Results of this study indicate that
hyperexcitability of the visual cortex in migraine goes beyond
visual area V1 and demonstrates for the first time a significant
difference in threshold for excitability of visual area V5 in
persons with migraine.
PMID: 11940694 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
32: Exp Brain Res. 2003 Jun;150(3):332-40.
Epub 2003 Apr 16. Related Articles, Links
Effects of repetitive transcranial magnetic
stimulation on visual evoked potentials: new insights in healthy
subjects.
Fumal A, Bohotin V, Vandenheede M, Seidel L, de Pasqua V, de
Noordhout AM, Schoenen J.
University Department of Neurology, CHR Citadelle Hospital, 4000
Liege, Belgium.
In a previous comparative study with migraineurs, we found in 24
normal subjects that the amplitude of the pattern-reversal
visual evoked potential (PR-VEP) in the first block of 100
responses and its habituation over 6 sequential blocks were
significantly decreased after 1 Hz repetitive transcranial
magnetic stimulation (rTMS), while 10 Hz rTMS had no significant
effect. We report here our results on the reproducibility of the
rTMS effect studied in ten of these subjects by repeating the
recordings for each frequency three times on different days. We
have also reanalysed the data obtained in 24 normal subjects,
looking separately at the results in those stimulated at an
intensity equal to phosphene threshold (group 1; n=14) and those
stimulated at 110% of motor threshold because of unelicitable
phosphenes (group 2; n=10). We finally determined the precise
duration of the rTMS effect. Despite some interindividual
variability, the effects of both rTMS frequencies on first block
amplitude, habituation between first and sixth block and
habituation slope over the six blocks were highly reproducible.
The only difference between the two groups of subjects was the
effect of 1 Hz rTMS on the second measured PR-VEP component.
Whereas first block amplitude of the first P1-N1 component and
habituation were decreased in both groups, such a decrease was
found for the second P1-N2 component only in group 1 stimulated
at phosphene threshold. The dishabituation of the N1-P1
component after 1 Hz rTMS was maximal at 15 min, but lasted up
to 33 min, while that of P1-N2 disappeared after 3 min. There
was a non-significant trend ( p=0.06) for a reduction of first
block amplitude after 10 Hz rTMS in the total group of subjects,
but no effect on habituation. The inhibitory effect of 1 Hz
rTMS, which reduces in healthy controls both first block PR-VEP
amplitude and habituation, probably by decreasing the
preactivation excitability level of the underlying visual
cortex, is thus reproducible and long lasting. Long trains of 10
Hz rTMS tend to attenuate reproducibly the cortical
preactivation level in normal subjects, but they do not affect
habituation at all, which contrasts with their effect in
migraineurs, in whom, as previously reported, they significantly
correct the habituation deficit. The absence of an effect of 1
Hz rTMS on PR-VEP P1-N2 in subjects stimulated at 110% of motor
threshold may be explained by the deeper anatomical location of
the cortical generators of this component and the lower
stimulation intensity used. Taken together our results confirm
that the effect of rTMS on the underlying cortex depends on
several variables such as frequency, intensity and level of
cortical preactivation.
PMID: 12698314 [PubMed - in process]
------------------------------------------------------------------------
33: Cephalalgia. 2001
Jun;21(5):611-6. Related Articles, Links
Altered cerebrovascular response pattern in
interictal migraine during visual stimulation.
Backer M, Sander D, Hammes MG, Funke D, Deppe M, Conrad B, Tolle
TR.
Department of Neurology, Technical University of Munich, Munich,
Germany.
A dysbalance of the cerebrovascular response during functional
activation of the brain has been postulated as a factor in the
pathophysiology of migraine. To determine the dynamic pattern of
the cerebrovascular response in migraineurs compared with a
control group, changes of the cerebral perfusion during cerebral
activation were studied with high temporal resolution by
functional transcranial Doppler sonography (fTCD). The cerebral
blood flow velocity (CBFV) in the right posterior cerebral
artery (PCA) and the left middle cerebral artery (MCA) was
measured simultaneously during visual stimulation in 19
interictal migraineurs and in 19 age- and sex-matched control
subjects. Data were analysed with a previously validated
technique based on automated stimulus-related averaging of the
CBFV. The MCA migraineurs exhibited a steady increase of CBFV
during the stimulation, while normal subjects showed a
habituation of the CBFV response. The lack of habituation in
migraineurs was significantly (P < or = 0.05) more pronounced
across patients with a high attack frequency (> or = 4 per
month) compared with migraineurs with a low attack frequency
(< 4 per month). In the PCA, compared with normal subjects,
migraineurs showed significantly (P < or = 0.05) stronger
CBFV changes at the beginning and after the end of stimulation,
with a slower decline to baseline. Data are in accordance with
electrophysiological findings in migraineurs. It is assumed that
a lack of habituation of the cerebrovascular response in
migraineurs might contribute to a disturbance of the metabolic
homeostasis of the brain that might induce migraine attacks.
PMID: 11472388 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
34: Headache. 2003 Mar;43(3):303.
Related Articles, Links
Modulation of trigeminal reflex
excitability in migraine: effects of attention and habituation
on the blink reflex.
De Tommaso M, Murasecco D, Libro G, Guido M, Sciruicchio V,
Specchio L, Gallai V, Puca F.
Int J Psychophysiol. 2002 Jun;44(3):239-249 The modulation of
trigeminal reflex excitability in migraine patients was
evaluated during the asymptomatic phase by studying the effects
of attention, habituation and preconditioning stimulus on the R2
and R3 components of the blink reflex (BR). Fifty patients
suffering from migraine without aura, 20 affected by migraine
with aura and 35 sex- and age-matched controls were selected. In
subgroups of migraine with-aura and without-aura patients, and
normal controls, the blink reflex was elicited during different
cognitive situations: (a) spontaneous mental activity; (b)
stimulus anticipation; (c) recognition of target numbers. In the
remaining subjects, R2 and R3 habituation was evaluated by
repetitive stimulation at 1, 5, 10, 15, 20, 25 and 30 s
intervals. The R2 and R3 recovery curves were also computed. A
reduced R3 threshold with a normal pain threshold was found in
migraine with-aura and without-aura patients; the R3 component
was not significantly correlated with the pain thresholds in
patients and controls. The R2 and R3 components were less
influenced by the warning of the stimulus in migraine
without-aura and migraine with-aura patients, in comparison with
the control group. A slight increase of both R2 and R3 recovery
after preconditioning stimulus was also observed in migraine
patients, probably caused by a phenomenon of trigeminal
hyperexcitability persisting after the last attack. The abnormal
BR modulation by alerting expresses in migraine a dysfunction of
adaptation capacity to environmental conditions, probably
predisposing to migraine. Comment: Further physiologic and
functional evidence for the interictal hyperexcitability of
neurons in patients with migraine, in this case trigeminal
neurons involved in the blink reflex. SJT
PMID: 12603665 [PubMed - as supplied by publisher]
------------------------------------------------------------------------
35: Curr Opin Neurol. 1998
Jun;11(3):205-9. Related Articles, Links
Brain excitability in migraine: evidence
from transcranial magnetic stimulation studies.
Aurora SK, Welch KM.
Henry Ford Hospital and Health Sciences Center, Department of
Neurology, Detroit, Michigan, USA.
Central neuronal hyperexcitability is proposed to be the
putative basis for the physiologic disturbances in migraine.
Because there are no structural disturbances in migraine, only
physiologic studies can provide insight into the underlying
mechanisms. Recently, transcranial magnetic stimulation has been
developed as a valuable research tool and can be used to study
brain function noninvasively. This article is a review of the
studies done in migraine using transcranial magnetic
stimulation.
Publication Types:
* Review
* Review, Tutorial
PMID: 9642537 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
36: No To Shinkei. 1998
Apr;50(4):361-5. Related Articles, Links
[Superficial siderosis of the central
nervous system: an electrophysiological study]
[Article in Japanese]
Shimo Y, Nohara C, Hotta M, Miwa H, Mizuno Y.
Department of Neurology, Juntendo University School of Medicine,
Tokyo, Japan.
Superficial siderosis of the central nervous system (SS) is a
rare neurological disorder characterized by symptoms such as
neurosensory hearing loss, ataxic gait, and spastic paraparesis.
Recently, magnetic resonance imaging (MRI) enables us to make a
clinical diagnosis. However, the exact pathophysiological
mechanism underlying this disorder remains uncertain. Although
iron chelation therapy has been attempted experimentally, it has
not been successful and there is no effective medical treatment
available. Towards the better understanding of the
pathophysiological mechanism underlying SS, we performed
electrophysiological studies, in which multiple evoked potential
studies were included, in 3 patients with SS. Somatosensory
evoked potentials (SEPs) evoked by median nerve stimulation were
all normal, but those evoked by the posterior tibial nerve
stimulation showed a significant delay of the latency of P40. In
the auditory brainstem response (ABR) studies, there were no
reproducible responses of the brainstem origin. In the blink
reflex studies, R2 latency was delayed in one patient. In visual
evoked potential (VEP) studies, the latency of P100 was delayed
in two of three patients, unless all the patients clinically
showed no visual symptom. The nerve conduction velocity studies
performed in peripheral nerves of upper and lower extremities
were all normal. The abnormal findings of ABR and SEP may
suggest that the acoustic nerve and the posterior funiculus of
the spinal cord are involved, respectively. These findings are
also in a good agreement with pathological findings of SS
reported in the literature. In SS, the hemosiderine accumulation
is usually less severe in the visual tract; however, the delay
of VEPs may suggest the latent dysfunctioning of the visual
system in SS. It is suggested that multiple evoked potential
study is useful for clinical evaluation of SS.
PMID: 9592826 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
37: Curr Opin Neurol. 2000
Jun;13(3):273-6. Related Articles, Links
Migraine: imaging the aura.
Aurora SK, Welch KM.
Neurophysiology Laboratory, Henry Ford Hospital, Detroit,
Michigan 48202, USA. sheaur@neuro.hfh.edu
We currently conceive of a migraine attack as originating in the
brain. Triggers of an attack initiate a depolarizing
neuroelectric and metabolic event likened to the spreading
depression of Leao. This event activates the headache and
associated features of the attack by mechanisms that remain to
be determined, but appear to involve either peripheral
trigeminovascular or brainstem pathways, or both. The
excitability of cell membranes, perhaps partly genetically
determined, is the brain's susceptibility to attacks. Factors
that increase or decrease neuronal excitability constitute the
threshold for triggering attacks. Using a model of visual
stress-induced migraine or by studying spontaneous attacks and
applying advanced imaging and neurophysiological methods,
results have been obtained that support spreading neuronal
inhibition as the basis of aura. This neuroelectric event is
accompanied by hyperoxia of the brain, possibly associated with
vasodilation. Evidence has also been obtained that the spreading
cortical event can activate the subcortical centers possibly
involved in nociception and associated symptoms of the migraine
attack. Susceptibility to migraine attacks appears to be related
to brain hyperexcitability. These newer techniques of functional
neuroimaging have confirmed the primary neural basis of the
migraine attack with secondary vascular changes, reconciling
previous theories into a neurovascular mechanism.
Publication Types:
* Review
* Review, Tutorial
PMID: 10871250 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
38: Curr Opin Neurol. 2003
Feb;16(1):5-13. Related Articles, Links
Migrainous vertigo: development of a
pathogenetic model and structured diagnostic interview.
Furman JM, Marcus DA, Balaban CD.
Department of Otolaryngology, University of Pittsburgh School of
Medicine, Pittsburgh, Pennsylvania 15213, USA. furman@pitt.edu
PURPOSE OF REVIEW: Vestibular symptoms occur frequently in
patients with migraine. This review refines recently proposed
diagnostic criteria for migraine-related vestibular symptoms,
and develops a pathophysiological model for the interface
between migraine and the vestibular system. RECENT FINDINGS: The
epidemiological link between migraine and vestibular symptoms
and signs suggests shared pathogenetic mechanisms. Links between
the vestibular nuclei, the trigeminal system, and
thalamocortical processing centers provide the basis for the
development of a pathophysiological model of migraine-related
vertigo. During the last year, several studies have increased
understanding of the relationship between migraine and
vestibular symptoms. A study of motion sickness and allodynia in
migraine patients supports the importance of central mechanisms
of sensitization for migraine-related vestibular symptoms. A
study has demonstrated effective treatment of vertigo with
migraine therapy. The identification of migrainous vertigo,
however, is hampered by a lack of standardized assessment
criteria for both clinical and research practices. The
application of published criteria for the diagnosis of
migrainous vertigo allows the development of a standardized,
structured assessment interview. SUMMARY: An understanding of
the relationship between migraine and the vestibular system
increases knowledge of the pathogenesis of both migraine and
vertigo. In addition, studies have identified successful
treatment, with standard migraine therapies, of vestibular
symptoms in patients with both migraine and vertigo. The use of
a standardized assessment tool to identify this unique
population of patients will help future studies to test both the
pathological model and effective treatment options.
Publication Types:
* Review
* Review, Tutorial
PMID: 12544852 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
39: Funct Neurol. 1986
Oct-Dec;1(4):357-61. Related Articles, Links
Bulbo-cortical pathways and their possible
relevance to migraine and epilepsy.
Lance JW, Adams RW, Lambert GA.
Facilitation of the visual evoked response from the reticular
formation in the cat has been shown to depend on nicotinic
cholinergic receptors distinct from the muscarinic cholinergic
receptors responsible for the arousal reaction. An increase in
the amplitude of visual evoked responses in migraineurs does not
therefore imply any change in reticulocortical activity of
relevance to epilepsy. Stimulation of locus ceruleus and nucleus
raphe dorsalis exerted comparatively minor effects on the visual
evoked response and did not alter the discharge rate of cortical
neurons in the resting state. It is concluded that the changes
in cerebral blood flow previously reported to result from
stimulation of these monoaminergic brainstem nuclei, which
resemble those observed in migraine, must be exerted directly on
the cortical microcirculation and not simply follow the
metabolic demand of cortical neurons. There is thus a place in
the management of migraine for pharmaceutical agents acting on
cerebral vessels even if the neural hypothesis for the mechanism
of migraine proves to be correct.
PMID: 3609865 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
40: Electromyogr Clin Neurophysiol. 2002
Apr-May;42(3):175-9. Related Articles, Links
Visual evoked potential & brainstem
auditory evoked potentials in acute attack & after the
attack of migraine.
Kochar K, Srivastava T, Maurya RK, Jain R, Aggarwal P.
Department of Medicine, S.P. Medical College, Bikaner-334003,
Rajasthan, India.
PURPOSE: To study the effect on visual evoked potential (VEP)
and brainstem auditory evoked potential (BAEP) at time of acute
attack and after 7 days of the attack of migraine. MATERIAL AND
METHODS: We studied BAEP and pattern reversal VEP in 25 patients
during acute attack and after 7 days of the attack. The
diagnosis of migraine was established according to criteria
given by international headache society (IHS). Peak and
interpeak latencies (IPL's) of BAEP and P100 latency of VEP were
the main criteria to judge abnormalities. RESULTS: There were
prolonged peak and interpeak latencies in BAEP and prolonged
peak latency (P100) in VEP at the time of acute attack of
migraine. The data of these abnormal recording were highly
significant. After 7 days when the attack was over, we recorded
the BAEP and VEP again. The observation obtained at this time
was comparable to normal values. CONCLUSIONS: From the
observation of this study we can safely conclude that in acute
attacks of migraine there may be some pathological changes in
different areas of brain and brainstem, producing changes in
evoked potential which are statistically highly significant.
However, these changes are reversible, as the values of BAEP
& VEP on 7th day after the attack were comparable to those
observed in normal healthy control.
PMID: 11977431 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
41: Pain. 2000 Mar;85(1-2):247-54.
Related Articles, Links
Intensity dependence of auditory evoked
cortical potentials in migraine families.
Siniatchkin M, Kropp P, Neumann M, Gerber W, Stephani U.
Institute of Medical Psychology, University of Kiel, Niemannsweg
147, D-24105, Kiel, Germany. siniatchkin@med.psych.uni-kiel.de
Intensity dependence of auditory evoked cortical potentials is
abnormal in migraine. This study investigated intensity
dependence in migraine and healthy families using group
comparisons and analysis of individual differences. Migraineurs
were characterized by a steeper amplitude/stimulus function
slope and more pronounced difference between the amplitudes of
N1-P2 on the more and the less intensive tones than healthy age
matched subjects. Apart from migraine, the age of the
participants was an important predictive variable of intensity
dependence. Analysis of individual differences revealed low
sensitivity and moderate specificity of intensity dependence for
migraine. Familial prevalence of intensity dependence among
first-degree relatives in migraine families was equal to that in
healthy families. These findings support the assumption that
high-intensity dependence reflects a functional CNS trait which
is more pronounced and prevalent in migraine, but may also be
found in healthy individuals and in other neuropsychiatric
disorders. Increased intensity dependence is only one of several
factors contributing to the risk for this form of headache.
Publication Types:
* Clinical Trial
PMID: 10692625 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
42: Cephalalgia. 1999
Apr;19(3):137-46. Related Articles, Links
Clinical neurophysiology in childhood
headache.
Puca F, de Tommaso M.
Clinica Neurologica I, Universita di Bari, Italy.
Electrophysiological studies in childhood headache are of
interest because of the need to make a clinical diagnosis and
also because of the efficacy of physiopathological studies in
juvenile age attributable to the recent outcome of the illness,
with less clinical modification by environmental factors or drug
use. Electrophysiological studies in childhood headache are
concerned with migraine and electroencephalographic (EEG)
evaluations; evoked potentials, event-related potentials and,
less often, electromyographic studies are also reported. Visual
analysis of EEG suggests an association between migraine and
epilepsy; quantitative EEG, visual and event-related evoked
potentials show fluctuating abnormalities, depending on the
occurrence of the migraine attacks and permanent anomalous
patterns related to the basic mechanisms underlying the disease.
Blink reflex studies might suggest a primary dysfunction of the
nociceptive control central system in children affected by
tension-type headache and migraine. The use of
neurophysiological procedures in juvenile migraine is considered
limited in clinical practice and of particular interest in
neurophysiological studies of headache.
Publication Types:
* Review
* Review, Tutorial
PMID: 10234460 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
43: J Neurol. 2002
Sep;249(9):1268-71. Related Articles, Links
Comparison of cortical excitability in
chronic migraine (transformed migraine) and migraine without
aura. A transcranial magnetic stimulation study.
Ozturk V, Cakmur R, Donmez B, Yener GG, Kursad F, Idiman F.
Dokuz Eylul University, Medical School, Department of Neurology,
35340, Izmir, Turkey. vesile.ozturk@deu.edu.tr
We studied the excitability of the motor cortex in patients with
migraine without aura (MWOA) (n = 20) and with chronic migraine
(CM) (n = 20) using transcranial magnetic stimulation (TMS). By
using a 90-mm circular coil placed over the vertex and recording
of the first dorsal interosseous muscle, we measured thresholds,
latencies and amplitudes of motor evoked potentials and duration
of cortical silent periods in patient groups and in controls (n
= 20). No differences were found between groups for threshold,
latency and amplitude values. However, the duration of the
cortical silent period was longer in CM patients, being
significantly different from both controls and MWOA. We suggest
that either this difference in cortical excitability may develop
during transformation from MWOA to CM or different
pathophysiological mechanisms may play a role in these two
headache syndromes.
PMID: 12242552 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
44: Rev Neurol. 1997
Oct;25(146):1611-6. Related Articles, Links
[Neurophysiological studies of headaches]
[Article in Spanish]
Munoz-Farjas E.
Servicio de Neurologia, Hospital Clinico Universitario de
Zaragoza, Espana.
INTRODUCTION AND OBJECTIVE: The diagnosis of headache is based
on the clinical criteria suggested by the IHS in 1988. The
neurophysiological examinations often used in the study of
headache may support the clinical diagnosis and give information
as to the prognosis. The objective of this paper is to review
the neurophysiological examinations most often used in the
clinical and pathological investigation of headache.
DEVELOPMENT: As shown by recent studies, the EEG is of little
value in the routine evaluation of a patient with headache.
However, it may be useful as an exploratory test for underlying
pathology in atypical headache or when intra-cranial pathology
is suspected. Evoked potentials, when used to study migraine,
show absence of Habituation (or Potentiation) in migraine
patients. This finding may represent abnormality in the
processing of information at a cortical level in these patients.
There is a tendency to unify the theory of neurone hypoxia and
the absence of Habituation in Migraine as a single hypothesis of
pathogenesis. Negative Contingent Variation has proved to be
clinically useful to optimize treatment in Migraine. The
electromyogram and Muscle Reflexes have been used in the study
of Tension Type Headaches, ES2 changes, showing brainstem
antinociceptive reflexes support the participation of a central
factor in the origin of chronic Tension Headache. CONCLUSION:
Neurophysiological tests may be useful in investigation of the
pathology of headache since they permit a functional study of
many neurone paths and the action of drugs on the central
nervous system.
Publication Types:
* Review
* Review, Tutorial
PMID: 9462993 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
45: Neurology. 1997 May;48(5):1462-4.
Related Articles, Links
Interictal cortical excitability to
magnetic stimulation in familial hemiplegic migraine.
van der Kamp W, MaassenVanDenBrink A, Ferrari MD, van Dijk JG.
Department of Neurology and Clinical Neurophysiology, Leiden
University Hospital, the Netherlands.
We studied interictal cortical excitability with magnetic
stimulation in controls, in patients with migraine with aura,
and in patients with familial hemiplegic migraine (FHM), in
which ictal hemiparesis occurs. Amplitudes (p < 0.05) and
amplitude ratios (p < 0.01) revealed heightened excitability
in migraine with aura when compared to controls. In patients
with FHM, mean thresholds were higher (p < 0.001) and
conduction times longer (p < 0.01) than in controls. In FHM,
amplitudes were lower on the ictally paretic side of the body
than on the other (p < 0.05). Patients with FHM may have
increased interictal cortical excitability, complicated by
decreased excitability of the affected side.
PMID: 9153495 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
46: Can J Neurol Sci. 1999 Nov;26 Suppl
3:S12-9. Related Articles, Links
Pathophysiology of migraine--new insights.
Hargreaves RJ, Shepheard SL.
Merck Research Laboratories, West Point PA 9486, USA.
Current theories propose that the primary dysfunction in
migraine occurs within the CNS and that this evokes changes in
blood vessels within pain-producing intracranial meningeal
structures that give rise to headache pain. Migraine is now
thought of as a neurovascular disorder. It has been proposed
that genetic abnormalities may be responsible for altering the
response threshold to migraine specific trigger factors in the
brain of a migraineur compared to a normal individual. The exact
nature of the central dysfunction that is produced in
migraineurs is still not clear and may involve spreading
depression-like phenomena and activation of brain stem
monoaminergic nuclei that are part of the central autonomic,
vascular and pain control centers. It is generally thought that
local vasodilatation of intracranial extracerebral blood vessels
and a consequent stimulation of surrounding trigeminal sensory
nervous pain pathways is a key mechanism underlying the
generation of headache pain associated with migraine. This
activation of the 'trigeminovascular system' is thought to cause
the release of vasoactive sensory neuropeptides, especially
CGRP, that increase the pain response. The activated trigeminal
nerves convey nociceptive information to central neurons in the
brain stem trigeminal sensory nuclei that in turn relay the pain
signals to higher centers where headache pain is perceived. It
has been hypothesized that these central neurons may become
sensitized as a migraine attack progresses. The 'triptan'
anti-migraine agents (e.g. sumatriptan, rizatriptan,
zolmitriptan naratriptan) are serotonergic agonists that have
been shown to act selectively by causing vasoconstriction
through 5-HT1B receptors that are expressed in human
intracranial arteries and by inhibiting nociceptive transmission
through an action at 5-HT1D receptors on peripheral trigeminal
sensory nerve terminals in the meninges and central terminals in
brain stem sensory nuclei. These three complementary sites of
action underlie the clinical effectiveness of the 5-HT1B/1D
agonists against migraine headache pain and its associated
symptoms.
Publication Types:
* Review
* Review, Tutorial
PMID: 10563228 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
47: Neurology. 2002 Apr
23;58(8):1234-8. Related Articles, Links
Acute migraine headache: possible
sensitization of neurons in the spinal trigeminal nucleus?
Kaube H, Katsarava Z, Przywara S, Drepper J, Ellrich J, Diener
HC.
Institute of Neurology, National Hospital for Neurology and
Neurosurgery, London, UK. holgerk@ion.ucl.ac.uk
OBJECTIVE: To investigate trigeminal sensory processing in
patients with migraine using a novel "nociception-specific"
blink reflex. METHODS: Seventeen patients with unilateral
migraine headache were studied within 6 hours of onset. Blink
reflexes were elicited with a standard stimulating electrode
(standard blink reflex) and concentric stimulating electrode
(nociception-specific blink reflex) during the acute migraine
attack, after treatment with IV lysine acetylsalicylate (1,000
mg) or oral zolmitriptan (5 mg) and interictally. RESULTS: After
standard stimulation, no differences were detected for the R1
and R2 onset latencies and areas under the curve (AUC) between
the different time points and the headache and nonheadache side.
Nociception-specific stimulation revealed a shortening of R2
onset latencies (44.3 +/- 5.4 ms for headache side vs 48.9 +/-
5.8 ms for nonheadache side) during the acute migraine attack
compared with the headache-free interval (49.8 +/- 5.3 vs 49.8
+/- 4.5 ms). The AUC of the R2 increased on the headache side by
680% and on the nonheadache side by 230% compared with the
headache-free interval. Drug treatment parallel to pain relief
increased the onset latencies (zolmitriptan: 48.0 +/- 8.2 ms for
headache side vs 52.3 +/- 7.6 ms for nonheadache side; lysine
acetylsalicylate: 48.0 +/- 5.0 ms for headache side vs 51.2 +/-
5.6 ms for nonheadache side) and reduced the AUC of R2
(zolmitriptan by 45% and lysine acetylsalicylate by 48%).
CONCLUSION: The data suggest temporary sensitization of central
trigeminal neurons during acute migraine attacks.
Publication Types:
* Clinical Trial
PMID: 11971092 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
48: Pain. 1999 Mar;80(1-2):191-200.
Related Articles, Links
Electrophysiological testing of the
trigeminofacial system: aid in the diagnosis of atypical facial
pain.
Jaaskelainen SK, Forssell H, Tenovuo O.
Department of Clinical Neurophysiology, Turku University Central
Hospital, Finland. satu.jaaskelainen@tyks.fi
The aim of this study was to evaluate the yield of objective
electrophysiological testing of the trigeminofacial system in
atypical facial pain (AFP). In addition to the clinical
neurological examination, two brainstem reflexes covering both
the peripheral parts and the central connections of the
trigeminal and the facial nerves, the blink and jaw reflexes (BR
and JR), were recorded in 17 AFP patients. The control group
consisted of 18 healthy volunteers with no history of facial
pain or chronic headache. The AFP patients could be divided into
three distinct groups on the basis of the clinical and
electrophysiological findings. (1) Major trigeminal neuropathy.
Four patients had clinical and electrophysiological signs of
trigeminal neuropathy (three patients with an afferent pattern
of abnormal BR, and one with absent JR on the clinically
affected side) despite normal findings in the MRI-scans of the
brain. Thus, electrophysiological testing may be more sensitive
than MRI in demonstrating pathology in some of the AFP patients.
(2) Minor trigeminal neuropathy. Seven patients had signs of
increased excitability of the BR in the form of uni- or
bilaterally abnormal (diminished or absent) habituation of the
R2 component of the BR; two of these patients also showed
clinical signs of trigeminal dysfunction, but the MRI-scans were
all normal. This deficient habituation of the BR indicates
increased excitability of the BR at brainstem level in nearly
50% of our AFP patients. (3) 'Idiopathic', no signs of
trigeminal neuropathy. Five patients had normal findings both in
the brainstem reflex recordings and in the clinical
examinations. Additionally, one patient had abnormal BAEP and
EEG recordings. On the group level, the AFP patients had
significantly higher thresholds of the tactile R1 component of
the BR than the control subjects. Electrophysiological testing
may offer a valuable tool for both the clinical evaluation, and
the scientific study of AFP.
Publication Types:
* Clinical Trial
PMID: 10204731 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
49: Pain. 2003 Jan;101(1-2):25-32.
Related Articles, Links
Abnormal brain processing of cutaneous pain
in patients with chronic migraine.
de Tommaso M, Valeriani M, Guido M, Libro G, Specchio LM, Tonali
P, Puca F.
Department of Psychiatric and Neurological Sciences, University
of Bari, Bari, Italy. m.detommaso@neurol.uniba.it
Syndromes with chronic daily headache include chronic migraine
(CM). The reason for the transformation of migraine into chronic
daily headache is still unknown. In this study, we aimed to
evaluate heat pain thresholds and event-related potentials
following CO(2)-laser thermal stimulation (LEPS) in hand and
facial regions in patients with CM, to show changes in
nociceptive brain responses related to dysfunction of pain
elaboration at the cortical level. The results were compared
with findings from normal control subjects and from subjects who
suffer from migraine without aura. The effects of stimulus
intensity, subjective pain perception and attention were
monitored and compared with features of the LEPS. Twenty-five CM
patients, 15 subjects suffering from migraine without aura and
15 normal control subjects were enrolled in the study. LEPS
amplitude variation was reduced in CM patients with respect to
the perceived stimulus intensity, in comparison with migraine
without aura patients and control subjects. In both headache
groups, the distraction from the painful laser stimulus induced
by an arithmetic task failed to suppress the LEPS amplitude, in
comparison with control subjects. These results suggest an
abnormal cortical processing of nociceptive input in CM
patients, which could lead to the chronic state of pain. In both
headache groups, an inability to reduce pain elaboration during
an alternative cognitive task emerged as an abnormal behaviour
probably predisposing to migraine.
PMID: 12507697 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
50: Neurosci Lett. 2001 Sep
7;310(1):37-40. Related Articles, Links
The blink reflex and the corneal reflex are
followed by cortical activity resembling the nociceptive
potentials induced by trigeminal laser stimulation in man.
de Tommaso M, Libro G, Guido M, Sciruicchio V, Puca F.
Interuniversity Center for the Study of Headache and
Neurotransmitter Disorders of the Central Nervous System,
Perugia, Roma, Sassari, Bari, Napoli, Firenze, Italy.
m.detommaso@neurol.uniba.it
Laser stimulation of the supraorbital regions evokes brain
potentials (LEPs) related to trigeminal nociception. The aim of
this study was to record the R2 component of the blink reflex
and the corneal reflex in 20 normal subjects, comparing the
scalp activity following these reflexes with the nociceptive
potentials evoked by CO2 laser stimulation of supraorbital
regions. Cortical and muscular reflexes evoked by stimulation of
the first trigeminal branch were recorded simultaneously. The R2
component of the blink reflex and the corneal reflex were
followed by two cortical peaks, which resembled morphologically
N-P waves of LEPs. The two peaks demonstrated a difference in
latency of approximately 40 ms, which is consistent with
activation time of nociception. This finding suggests that these
reflexes are induced by activation of small pain-related fibers.
Publication Types:
* Clinical Trial
PMID: 11524152 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
51: Electroencephalogr Clin Neurophysiol.
1989 Oct;73(4):285-94. Related Articles, Links
Difference of steady-state visual evoked
potentials in classic and common migraine.
Nyrke T, Kangasniemi P, Lang AH.
Department of Clinical Neurophysiology, University Central
Hospital, Turku, Finland.
The present study was designed to find evidence for the neural
hypothesis of migraine and to evaluate possible interictal
differences in the two varieties of migraine by
electrophysiological means. Steady-state visual evoked
potentials (SVEPs) in response to sinusoidally modulated light
were measured in 20 patients with classic migraine and compared
with those of 30 common migraineurs and 49 reference subjects.
SVEPs to stimuli at 10-24 Hz were recorded occipitally from a
pair of midline electrodes and, in classic migraineurs and
controls, additionally from left and right occipital areas. The
response was processed by the Fast Fourier Transform and
automatically analysed. The fundamental component of the midline
response to medium frequency stimuli (16-22 Hz) appeared normal
in patients with classic migraine, contrary to an augmented
response in common migraineurs (ANOVA between groups, P =
0.006). In classic migraine the 2nd harmonic component was
attenuated (P less than 0.01 at 18-20 Hz) and the amount of
strong interhemispheric f1 asymmetries was increased in about
half of the patients. The groups also diverged significantly in
the SVEP dynamics during stimulation. The results support the
hypothesis of a primary neural disorder in both types of
migraine. Different sites and mechanisms of brain dysfunction in
classic and common migraine are suggested. Hypothetical
neuroanatomical correlates for the abnormalities are presented.
PMID: 2477215 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
52: Neurology. 2000;55(9 Suppl
2):S36-45. Related Articles, Links
Functional neuroimaging: enhanced
understanding of migraine pathophysiology.
Cutrer FM, O'Donnell A, Sanchez del Rio M.
Partners Headache Center, Department of Neurology, Massachusetts
General Hospital, Boston, 02129, USA.
Research into migraine pathophysiology has been hampered by the
episodic nature and unpredictable onset of migraine attacks.
Recently, newer imaging techniques have been providing
noninvasive methods of studying metabolism and hemodynamics in
the brains of migraineurs during and between acute attacks.
133Xe blood flow techniques, transcranial Doppler, and SPECT
have all been employed to investigate hemodynamic changes during
migraine aura. PET has been useful in the study of migraine
without aura, with findings of increased blood flow related to
pain in cortical areas and in the medial brainstem. Currently,
three functional MRI imaging techniques are being used in
migraine research. Diffusion-weighted imaging has shown normal
findings in measures of the ability of neurons to maintain
osmotic gradients. Studies using perfusion-weighted imaging have
shown alterations in relative cerebral blood flow (CBF),
relative cerebral blood volume, and mean transit time during
migraine visual aura. The blood oxygen level-dependent technique
can supply information related to neuronal activation during
acute migraine aura. MRS has been used with mixed success to
look for evidence of abnormal energy metabolism in the brains of
migraineurs. Magnetoencephalography studies support the presence
of a spreading depression-like phenomenon in migraine with aura.
Two groups have used transcranial magnetic stimulation to assess
whether neurons in the occipital cortex are hyperexcitable,
predisposing patients to develop aura symptoms. Despite
conflicting findings, migraine with visual aura appears to be
generally associated with transient decreases in regional CBF.
Publication Types:
* Review
* Review, Tutorial
PMID: 11089518 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
53: Indian J Physiol Pharmacol. 1998
Apr;42(2):172-88. Related Articles, Links
Average evoked potentials--clinical
applications of short latency responses.
Tandon OP.
Department of Physiology, University College of Medical
Sciences, Shahdar, Delhi.
Many clinical neurophysiology laboratories have added average
evoked potential studies to their routine procedures as evoked
potential recording methods are non invasive, highly objective
and informative. Indeed, short latency brainstem auditory evoked
potentials as well as short and intermediate latency cortical
evoked potentials, lately have proved to be valuable clinical
tools for objectively testing afferent functions in patients
with neurological and sensory disorders. The averaged evoked
potential responses (EPR) have been widely used in clinical
practice to record the changes in the electrical potentials that
occur within the central nervous system (CNS) of the patient in
response to an external stimulus. Two types of evoked potentials
are usually recorded. 1-Stimulus related, short latency evoked
potentials, which represent an obligate neuronal response to a
given stimulus and both the amplitudes and latencies of these
depend on the physical characteristics of the eliciting
stimulus. In this category brainstem auditory evoked potentials
(BAEPs), visual evoked potentials (VEPs) and somatosensory
evoked potentials (SEPs), have normal values for latencies,
amplitudes of waves and characteristic wave form. Any
abnormality of these reflects excitation, conduction block in
the specific pathways in the CNS. Certain abnormalities in EPR
reflect subclinical involvement of CNS even before the disease
clinically manifests. Abnormality in BAEPs can in addition,
depict the exact site of lesion in the brainstem auditory
pathways. Same is true for SEPs where abnormalities in far-field
or near-field components, reflect lesions at the plexus, spinal
cord, brainstem or thalamo-cortical regions respectively. 2- The
event related potentials (ERPs) can be recorded in response to
an external stimulus to which person is attentive or an event
requiring cognition, discrimination, or reaction to the target
stimulus. P300 is one such ERP, helpful in distinguishing
between disorders such as dementia and depression. This first
review gives a bird's eyeview of the essentials, methods,
interpretation and clinical applications of stimulus evoked
short latency (brainstem auditory, visual and somatosensory)
responses in human beings.
Publication Types:
* Review
* Review, Tutorial
PMID: 10225045 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
54: Semin Neurol. 1997;17(4):335-41.
Related Articles, Links
Pathogenesis of migraine.
Welch KM.
Department of Neurology, Henry Ford Hospital and Health Sciences
Center, Detroit, Michigan 48202, USA.
Prevailing hypotheses for the mechanisms of migraine are
reviewed. Models of aura mechanisms include transient cerebral
ischemia and spreading depression. Models of headache involve
trigeminovascular and brainstem mechanisms. The ability to
trigger an attack may depend on a threshold of brain
excitability. Mitochondrial disorder, magnesium deficiency, and
abnormality of presynaptic calcium channels may be responsible
for neuronal hyperexcitability between attacks. It remains to be
determined whether cortical or brainstem centers generate the
attack.
Publication Types:
* Review
* Review, Tutorial
PMID: 9474713 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
55: Acta Neurol Scand. 2001
Nov;104(5):301-7. Related Articles, Links
Asymmetric scalp distribution of pattern
visual evoked potentials during interictal phases in migraine.
Logi F, Bonfiglio L, Orlandi G, Bonanni E, Iudice A, Sartucci F.
Department of Neuroscience, Institute of Neurology, University
of Pisa, Italy.
The N70 and P100 components of transient pattern visual evoked
potentials (P-VEPs) were measured in migraine patients, with and
without aura, and in normal subjects in order to evaluate their
latency, amplitude and occipital scalp distribution. The aim was
to find any typical electrophysiological abnormalities in
migraine. P-VEP N70 and P100 were analyzed in 59 patients
without any known visual field defect. Mean latency and
amplitude values were within normal ranges for either N70 and
P100 all over the occipital scalp; the only significant
abnormality we found was related to the absolute right-left
amplitude ratio either for N70 and P100 waves, providing an
asymmetry in P-VEP scalp distribution; this finding was detected
in 78.9% of patients with aura and 72.5% without aura. Our
results show that in migraine patients, both P-VEP waves N70 and
P100, have an asymmetric topographic distribution, even during
interictal phases, that can be explained by a cortical
disturbance in agreement with the neural hypothesis of headache.
PMID: 11696025 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
56: Clin Neurophysiol. 2003
May;114(5):889-93. Related Articles, Links
Decreased habituation of the R2 component
of the blink reflex in migraine patients.
De Marinis M, Pujia A, Natale L, D'arcangelo E, Accornero N.
Department of Neurological Sciences, La Sapienza University,
Viale dell' Universita 30, 00185 Rome, Italy.
milena.demarinis@uniroma1.it
OBJECTIVE: Activation of the trigemino-vascular system as well
as of brainstem trigeminal nuclei are thought to play an
important role in migraine. The aim of this study was to
investigate the habituation phenomenon of the blink reflex in 30
headache-free migraine patients and 30 control subjects.
METHODS: An electromyographic device with a specific habituation
test program was used to elicit and record blink reflex
responses on both the right and left sides, and to randomly
repeat the stimulations at different time intervals in order to
induce habituation. RESULTS: Whereas the R1 and R2 latencies,
amplitudes and areas in the basal assessment were similar in
patients and control subjects, the blink reflex habituation
responses were markedly reduced in migraine patients who had a
migraine attack within 72 h after testing (group A). In these
patients, the differences between the R2 areas, obtained when
stimuli were delivered at subsequent time intervals ranging
between 10-5, 5-4, 4-3 and 3-2 s, were statistically different
(P<0.001) from those of the patients who had a migraine
attack after a longer time interval (group B) and control
subjects. CONCLUSIONS: Our data suggest that the brainstem
pathways involved in the blink reflex may be activated in the
premonitory phase of migraine attacks, probably through
mechanisms that involve dopaminergic function.
PMID: 12738435 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
57: J Neurol Sci. 2001 Mar
1;184(2):139-41. Related Articles, Links
Visual evoked potential changes in
migraine. Influence of migraine attack and aura.
Yilmaz M, Bayazit YA, Erbagci I, Pence S.
Department of Neurology, Faculty of Medicine, Gaziantep
University, Kolejtepe, Gaziantep, Turkey.
OBJECTIVE: To assess the visual evoked potential (VEP) changes
in migraines with and without aura. STUDY DESIGN: A clinical
study in which the VEP results of 45 migraineurs (study group)
and 22 healthy volunteers (control group) were compared. Of 45
migraineurs, 29 had migraine with aura (MA) and 16 had migraine
without aura (MOA), and they were examined both during and
between the migraine attacks. METHODS: The patients and healthy
controls underwent VEP assessment. On VEP recording, mono-ocular
stimulation was performed by means of the pattern reversal check
board. The latencies of N1, P1 and N2, and the N1--P1 amplitude
were noted. The following comparisons were made between NI, P1
and N2 latencies and N1--P1 amplitudes of the migraine and
control groups; during and between attack the VEP results of the
patients with MA and MOA. RESULTS: The VEP results of the
migraineurs and healthy controls were similar (P>0.05). The
during attack results of MA, during and between attack results
of MOA, and the results of the control group were also similar
(P>0.05). N2 latency significantly elongated in patients with
MA in the attack free period than it was during the attack
(P=0.01), and was also longer than it was in the control group
(P=0.01). CONCLUSIONS: There is involvement of the visual
pathway in MA rather than MOA, and differentiation between these
subtypes of the migraine disease may be performed on the basis
of VEP findings manifesting by the prolongation of the N2 wave
latency. This contention should be confirmed by further studies.
Publication Types:
* Clinical Trial
PMID: 11239947 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
58: Int J Psychophysiol. 2002
Jun;44(3):239-49. Related Articles, Links
Modulation of trigeminal reflex
excitability in migraine: effects of attention and habituation
on the blink reflex.
de Tommaso M, Murasecco D, Libro G, Guido M, Sciruicchio V,
Specchio LM, Gallai V, Puca F.
Clinical Neurologica I Policlinico, Piazza G. Cesare II, 70124,
Bari, Italy. m.detommaso@neurol.uniba.it
The modulation of trigeminal reflex excitability in migraine
patients was evaluated during the asymptomatic phase by studying
the effects of attention, habituation and preconditioning
stimulus on the R2 and R3 components of the blink reflex (BR).
Fifty patients suffering from migraine without aura, 20 affected
by migraine with aura and 35 sex- and age-matched controls were
selected. In subgroups of migraine with-aura and without-aura
patients, and normal controls, the blink reflex was elicited
during different cognitive situations: (a) spontaneous mental
activity; (b) stimulus anticipation; (c) recognition of target
numbers. In the remaining subjects, R2 and R3 habituation was
evaluated by repetitive stimulation at 1, 5, 10, 15, 20, 25 and
30 s intervals. The R2 and R3 recovery curves were also
computed. A reduced R3 threshold with a normal pain threshold
was found in migraine with-aura and without-aura patients; the
R3 component was not significantly correlated with the pain
thresholds in patients and controls. The R2 and R3 components
were less influenced by the warning of the stimulus in migraine
without-aura and migraine with-aura patients, in comparison with
the control group. A slight increase of both R2 and R3 recovery
after preconditioning stimulus was also observed in migraine
patients, probably caused by a phenomenon of trigeminal
hyperexcitability persisting after the last attack. The abnormal
BR modulation by alerting expresses in migraine a dysfunction of
adaptation capacity to environmental conditions, probably
predisposing to migraine.
PMID: 12031298 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
59: J Neurol Neurosurg Psychiatry. 1988
Jan;51(1):43-9. Related Articles, Links
Argon laser induced single cortical
responses: a new method to quantify pre-pain and pain
perceptions.
Bjerring P, Arendt-Nielsen L.
Department of Dermatology, Marselisborg Hospital, Aarhus,
Denmark.
The shape (amplitude and latency) of single cortical responses
to argon laser stimulation was found to match six perceptual
classes: three pre-pain and three pain. The amplitude of the
pain related single cortical responses correlated with the
perceived feeling of pain. Easy detectable responses were
obtained because habituation to the stimuli was reduced and a
high degree of attention was given to each stimulus. Single
cortical responses to argon laser stimuli are suggested as a new
quantitative technique with application in the assessment of
function in the thermal and nociceptive pathways.
PMID: 3351530 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
60: Headache. 2001 Jun;41(6):565-72.
Related Articles, Links
Visual cortex excitability in migraine with
and without aura.
Mulleners WM, Chronicle EP, Palmer JE, Koehler PJ, Vredeveld JW.
Departments of Neurology, Atrium Medical Center, Heerlen, The
Netherlands.
OBJECTIVES: Previous research using transcranial magnetic
stimulation has produced equivocal findings concerning
thresholds for the generation of visual phosphenes in migraine
with aura. These studies were methodologically varied and did
not systematically address cortical excitability in migraine
without aura. We therefore studied magnetophosphene thresholds
in both migraine with aura and migraine without aura compared
with headache-free controls. METHODS: Sixteen subjects with
migraine with aura and 12 subjects with migraine without aura
were studied and compared with 16 sex- and age-matched controls.
Using a standardized transcranial magnetic stimulation protocol
of the occipital cortex, we assessed the threshold stimulation
intensity at which subjects just perceived phosphenes via a
method of alternating course and fine-tuning of stimulator
output. RESULTS: There were no significant differences across
groups in the proportion of subjects seeing phosphenes. However,
the mean threshold at which phosphenes were reported was
significantly lower in both migraine groups (migraine with
aura=47%, migraine without aura=46%) than in controls (66%).
Moreover, there was no significant correlation between
individual phosphene threshold and the time interval to the
closest migraine attack. CONCLUSION: Our findings confirm that
the occipital cortex is hyperexcitable in the migraine
interictum, both in migraine with and without aura.
PMID: 11437892 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
61: Can J Neurol Sci. 1984
Feb;11(1):60-3. Related Articles, Links
Electrophysiological studies in five cases
of abetalipoproteinemia.
Lowry NJ, Taylor MJ, Belknapp W, Logan WJ.
Auditory brainstem responses (ABRs), visual and somatosensory
evoked responses (VEPs and SEPs) and nerve conduction studies
were conducted in 5 patients with abetalipoproteinemia. The ABRs
were normal in all cases. The VEPs were of normal amplitude but
of increased latencies in two patients. The four eldest patients
had delayed cortical SEPs but normal peripheral sensory nerve
conduction studies. The peripheral motor conduction velocities
were normal in all cases. The peripheral sensory studies showed
normal velocity when a response was seen; however, the amplitude
of the response was often reduced or it was absent. The
electrophysiological studies reported here support a model of
axonal loss of large myelinated fibres with secondary
demyelination in abetalipoproteinemia.
PMID: 6704795 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
62: Muscle Nerve. 1999
Apr;22(4):508-16. Related Articles, Links
Assessment of trigeminal small-fiber
function: brain and reflex responses evoked by CO2-laser
stimulation.
Cruccu G, Romaniello A, Amantini A, Lombardi M, Innocenti P,
Manfredi M.
Dipartimento Scienze Neurologiche, Viale Universita 30, Roma,
Italy.
Laser pulses selectively excite mechano-thermal nociceptors and
evoke brain potentials that may reveal small-fiber dysfunction.
We applied CO2-laser pulses to the perioral and supraorbital
regions and recorded the scalp laser-evoked potentials (LEPs)
and reflex responses in the orbicularis oculi, masticatory, and
neck muscles in 30 controls and 10 patients with facial sensory
disturbances. Low-intensity pulses readily evoked scalp
potentials consisting of a negative component with a latency of
165 ms followed by a positive component at 250 ms. In vertex
recordings, the amplitude of LEPs exceeded 30 microV. Although
only high-intensity pulses evoked reflex responses, some
subjects showed--even to low-intensity pulses--an orbicularis
oculi (blink-like) response that markedly contaminated the scalp
recording. Scalp LEPs were abnormal in patients with hypalgesia
and normal trigeminal reflexes and normal in patients with
normal pain sensitivity and abnormal trigeminal reflexes.
Possibly because of the high receptor density in this area and
the short conduction distance, laser stimulation of the
trigeminal territory yields low-threshold and large LEPs, which
are useful for detecting dysfunction in peripheral and central
pain pathways.
PMID: 10204787 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
63: Headache. 1992 Jul;32(7):345-7.
Related Articles, Links
Menstrual migraine without aura: cortical
excitability to magnetic stimulation.
Bettucci D, Cantello R, Gianelli M, Naldi P, Mutani R.
Department of Neurology, University School of Medicine of
Novara, Italy.
The purpose of the present study was the evaluation of the
excitability threshold and the central motor conduction time
(CCT) studied by means of electromagnetic cortical stimulation
in ten subjects affected by menstrual migraine without aura,
both in the ictal and the interictal period. The patients were
chosen from among a group of 254 outpatients affected by
migraine, diagnosed according to the International Headache
Society criteria. The control group consisted of ten healthy
female subjects. As far as CCTs were concerned no differences
emerged between patients and controls. However in the patient
group we found a significant increase in the excitability
threshold values, both in the ictal and the interictal period,
and in both hemispheres. If confirmed, the increased
excitability threshold may be a useful neurophysiological
correlate of migraine without aura.
PMID: 1526765 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
64: Cephalalgia. 1999
Jun;19(5):485-91. Related Articles, Links
Comment in:
* Cephalalgia. 1999 Jun;19(5):477.
Dynamic changes of cognitive habituation
and serotonin metabolism during the migraine interval.
Evers S, Quibeldey F, Grotemeyer KH, Suhr B, Husstedt IW.
Department of Neurology, University of Munster, Germany.
everss@uni-muenster.de
Migraine patients show a specific cognitive processing with a
loss of habituation in the interval and a normal habituation in
the attack as measured by event-related potentials (ERPs). It is
unknown whether the loss of habituation changes during the
migraine interval or is a stable state. Serotonin (5HT)
metabolism is involved in the pathophysiology of migraine and
also in the generation of ERPs. We enrolled 14 patients with
regular migraine attacks in order to measure visually evoked
ERPs repetitively during the migraine interval and in the
migraine attack. Cognitive habituation was evaluated by analysis
of P3 latency. Platelet serotonin content and free serotonin
plasma level were measured at the same time points. The loss of
habituation increased continuously during the migraine interval
and abruptly normalized in the migraine attack (p < 0.05,
time series analysis). The platelet 5HT content decreased
significantly in the migraine attack (p < 0.03) and was at
its maximum in the middle of the interval. The P3 latency was
significantly increased in the attack (p < 0.01) and was
significantly inversely correlated with the platelet 5HT content
(r = -0.44, p < 0.001). Free 5HT plasma levels did not show
any significant change. Our findings suggest that loss of
cognitive habituation continuously increases during the migraine
interval until its normalization in the migraine attack. This
phenomenon cannot be attributed to serotonergic transmission. In
patients with regular changes of cognitive habituation before
the migraine attack, it might be possible to predict the attack
by analysing ERPs.
PMID: 10403063 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
65: Cephalalgia. 1990
Dec;10(6):317-29. Related Articles, Links
Event-related slow potentials and
associated catecholamine function in migraine.
Nagel-Leiby S, Welch KM, D'Andrea G, Grunfeld S, Brown E.
Department of Neurology, Henry Ford Hospital, Detroit, MI 48202.
Plasma norepinephrine and dopamine and event-related slow
potentials were measured at menses and ovulation in migraine
with and without aura relative to normal subjects. The results
indicated that at menses, but not ovulation, plasma dopamine was
increased and norepinephrine was decreased relative to normal.
This catecholamine imbalance was greater in migraine without
aura than in migraine with aura. Conversely, event-related slow
potentials measured over the posterior cortex at ovulation but
not at the menses was altered relative to normal. Early epoch
negativity was reduced in migraine with aura, whereas late epoch
negativity was reduced in migraine without aura. The results
suggested that (a) migraine without aura may involve dynamic
shifts in the function of both norepinephrine and dopamine
responsive neurons; (b) pathophysiology of migraine with aura is
less dependent on catecholamine imbalance (norepinephrine alone
affected); (c) these pathophysiological mechanisms are most
prevalent in or restricted to posterior cortical regions but may
be modulated by brainstem mechanisms.
PMID: 2289233 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
66: J Physiol. 2002 Apr 15;540(Pt
2):623-33. Related Articles, Links
Modulation of human corticomotor
excitability by somatosensory input.
Kaelin-Lang A, Luft AR, Sawaki L, Burstein AH, Sohn YH, Cohen
LG.
Human Cortical Physiology Section, NINDS, National Institutes of
Health, Bethesda, MD 20892, USA.
In humans, somatosensory stimulation results in increased
corticomotoneuronal excitability to the stimulated body parts.
The purpose of this study was to investigate the underlying
mechanisms. We recorded motor evoked potentials (MEPs) to
transcranial magnetic stimulation (TMS) from abductor pollicis
brevis (APB), first dorsal interosseous (FDI), and abductor
digiti minimi (ADM) muscles. MEP amplitudes, recruitment curves
(RC), intracortical inhibition (ICI), intracortical facilitation
(ICF), resting (rMT) and active motor thresholds (aMT) were
recorded before and after a 2-h period of ulnar nerve electrical
stimulation at the wrist. Somatosensory input was monitored by
recording somatosensory evoked potentials. To differentiate
excitability changes at cortical vs. subcortical sites, we
recorded supramaximal peripheral M-responses and MEPs to
brainstem electrical stimulation (BES). In order to investigate
the involvement of GABAergic mechanisms, we studied the
influence of lorazepam (LZ) (a GABA(A) receptor agonist)
relative to that of dextromethorphan (DM) (an NMDA receptor
antagonist) and placebo in a double-blind design. We found that
somatosensory stimulation increased MEP amplitudes to TMS only
in the ADM, confirming a previous report. This effect was
blocked by LZ but not by either DM or placebo and lasted between
8 and 20 min in the absence of (i) changes in MEPs elicited by
BES, (ii) amplitudes of early somatosensory-evoked potentials or
(iii) M-responses. We conclude that somatosensory stimulation
elicited a focal increase in corticomotoneuronal excitability
that outlasts the stimulation period and probably occurs at
cortical sites. The antagonistic effect of LZ supports the
hypothesis of GABAergic involvement as an operating mechanism.
Publication Types:
* Clinical Trial
PMID: 11956348 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
67: Neurology. 1999 Mar
23;52(5):1044-9. Related Articles, Links
Physiology of perception: cortical
stimulation and recording in humans.
Ray PG, Meador KJ, Smith JR, Wheless JW, Sittenfeld M, Clifton
GL.
Department of Neurology, Medical College of Georgia, Augusta
30912, USA.
OBJECTIVES: 1) To determine the effect of stimulus train
duration (TD) on sensory perception using direct stimulation of
somatosensory and visual cortices. 2) To investigate the
occurrence of evoked potentials in response to stimulation that
is subthreshold for perception. BACKGROUND: Studies of the
mechanisms of conscious perception using direct cortical
stimulation and recording techniques are rare. The clinical
necessity to implant subdural electrode grids in epilepsy
patients undergoing evaluation for surgery offers an opportunity
to examine the role of stimulus parameters and evoked potentials
in conscious perception. METHODS: Subjects included epilepsy
patients with grids over somatosensory or occipital cortex.
Single pulses (100 microseconds) and stimulus trains were
applied to electrodes, and thresholds for perception were found.
Evoked potentials were recorded in response to peripheral
stimulation at intensities at, above, and below sensory
threshold. RESULTS: During cortical stimulation, sensory
threshold changed little for stimulus trains of 250 milliseconds
and longer, but increased sharply as TD decreased below this
level. Primary evoked activity was recorded in response to
peripheral stimulations that were subthreshold for conscious
perception. CONCLUSIONS: The results confirm a previous report
of the effects of stimulus TD on sensory threshold. However, no
motor responses occurred following somatosensory stimulation
with short trains, as previously reported. The TD threshold
pattern was similar in visual cortex. In agreement with the
previous report, early components of the primary evoked response
were not correlated with conscious sensory awareness.
PMID: 10102426 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
68: J Clin Neurophysiol. 2002
Aug;19(4):294-306. Related Articles, Links
Transcranial magnetic stimulation and
epilepsy.
Macdonell RA, Curatolo JM, Berkovic SF.
Department of Neurology, Austin & Repatriation Medical
Centre, Heidelberg, Victoria, Australia.
rmac@austin.unimelb.edu.au
Transcranial magnetic stimulation has been used to study
generalized and focal epilepsies for more than a decade. The
technique appears safe and has yielded important information
about the mechanisms underlying epilepsy. Transcranial magnetic
stimulation findings differ depending on the epilepsy syndrome,
lending support to the concept that there are distinct
pathophysiologies underlying each condition. In most studies of
generalized epilepsies, transcranial magnetic stimulation has
indicated a state of relative hyperexcitability of excitatory
cortical interneurons and possibly inhibitory interneurons as
well, which can be reversed through the actions of
anticonvulsant medications. Transcranial magnetic stimulation
studies in patients with a seizure focus in the motor cortex
indicate increased cortical excitability and reduced inhibition,
but in patients with seizure foci located elsewhere the findings
are similar to those in generalized epilepsies. Transcranial
magnetic stimulation has also been used to study the mode of
action of anticonvulsants and may prove to be a useful means of
testing the potential for new drugs to act as anticonvulsants.
Repetitive transcranial magnetic stimulation may prove to have a
therapeutic role by producing long-lasting cortical inhibition
after a train of impulses.
Publication Types:
* Review
* Review, Tutorial
PMID: 12436086 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
69: Appl Psychophysiol Biofeedback. 2002
Sep;27(3):203-13. Related Articles, Links
On the pathophysiology of migraine--links
for "empirically based treatment" with neurofeedback.
Kropp P, Siniatchkin M, Gerber WD.
Institute of Medical Psychology, University of Kiel, Niemannsweg
147, D-24105 Kiel, Germany. kropp@med-psych.uni-kiel.de
Psychophysiological data support the concept that migraine is
the result of cortical hypersensitivity, hyperactivity, and a
lack of habituation. There is evidence that this is a brain-stem
related information processing dysfunction. This cortical
activity reflects a periodicity between 2 migraine attacks and
it may be due to endogenous or exogenous factors. In the few
days preceding the next attack slow cortical potentials are
highest and habituation delay experimentally recorded during
contingent negative variation is at a maximum. These striking
features of slow cortical potentials are predictors of the next
attack. The pronounced negativity can be fed back to the
patient. The data support the hypothesis that a change in
amplitudes of slow cortical potentials is caused by altered
habituation during the recording session. This kind of
neurofeedback can be characterized as "empirically based"
because it improves habituation and it proves to be clinically
efficient.
Publication Types:
* Review
* Review, Tutorial
PMID: 12206051 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
70: Cephalalgia. 1999 Oct;19(8):718-24;
discussion 697-8. Related Articles, Links
Personality and response to repeated visual
stimulation in migraine and tension-type headaches.
Wang W, Wang GP, Ding XL, Wang YH.
Anhui Institute of Stereotactic Neurosurgery, Hefei, China.
wang_wei@mail.hf.ah.cn
Migraine sufferers potentiate their visual evoked potentials
(VEPs) from a short period of 2 min to a longer period of 15
min. As a lack of habituation is linked to higher level arousal,
we thus hypothesized that short-term VEP potentiation might be
correlated with an arousal-related personality trait. We
therefore carried out short-term VEPs, Plutchik-van Praag's
Depression Inventory, Zuckerman's Sensation-Seeking Scales (Form
V), and Zuckerman-Kuhlman's Personality Questionnaire in 26
healthy subjects, 22 patients suffering from migraine without
aura between attacks, 13 episodic and 20 chronic tension-type
headaches. The chronic tension-type headache sufferers showed
increased depression compared with other groups, which might be
a consequence of the headache itself. Migraines, however, showed
steeper habituation slopes of N1-P1 and P1-N2, decreased thrill
and adventure-seeking, and general sensation-seeking than
healthy controls; in addition, the habituation slope of P1-N2
was positively correlated with experience-seeking in migraine.
The short-term VEP potentiation and the decreased thrill and
adventure-seeking and general sensation-seeking in migraine
might be related to a high level of cortical arousal and a low
5HT neurotransmission. In compliance with the long-term VEP
study, the positive correlation between the P1-N2 habituation
slope and experience-seeking in migraine suggests a continuous
metabolic overload for the brain interictally, which can trigger
the activation of a migraine attack.
Publication Types:
* Clinical Trial
* Controlled Clinical Trial
PMID: 10570726 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
71: J Neurol Neurosurg Psychiatry. 1987
Apr;50(4):416-22. Related Articles, Links
Laterality of pain in migraine
distinguished by interictal rates of habituation of
electrodermal responses to visual and auditory stimuli.
Gruzelier JH, Nicolaou T, Connolly JF, Peatfield RC, Davies PT,
Clifford-Rose F.
Support is provided for a primary neural factor in migraine by
studies in autonomic responsiveness to sensory stimuli in
relation to the laterality of pain. Migraineurs with
consistently lateralised headaches were found in two studies to
exhibit extremes of autonomic responsiveness to sensory stimuli
during the interictal phase. The direction of responsiveness was
predictive of the laterality of pain; left-sided pain was
associated with under-responsiveness and fast habituation,
right-sided pain with over-responsiveness and slow habituation.
Bipolarity in rate of habituation is consistent with a defect in
a regulatory mechanism that controls regional cerebral
activation such as the diffuse thalamic projection system.
PMID: 3585352 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
72: Brain Res Cogn Brain Res. 2003
May;16(3):488-91. Related Articles, Links
Reductions in CI amplitude after repetitive
transcranial magnetic stimulation (rTMS) over the striate
cortex.
Schutter DJ, van Honk J.
Affective Neuroscience Section, Helmholtz Research Institute,
Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The
Netherlands. d.schutter@fss.uu.nl
Slow repetitive transcranial magnetic stimulation (rTMS) is a
method capable of transiently inhibiting cortical excitability
and disrupting information processing in the visual system. This
method can be used to topographically map the functional
contribution of different cortical brain areas in visual
processing. An early electrophysiological component, the CI is
argued to reflect early visual processing. In addition,
source-localization studies have provided evidence for the
assumption that the striate cortex is the underlying neural
generator of CI. In the present placebo-controlled, crossover
study, slow rTMS was applied in order to further investigate the
relationship between the striate cortex and the CI component.
Based on the inhibitory effects of slow rTMS, a reduction in CI
amplitude and an increase in latency were expected. Compared to
placebo stimulation, slow rTMS over the striate cortex resulted
in significant decreases of the CI amplitude, but did not affect
latency. The present study provides causal evidence for the
involvement of the striate cortex in generating the CI
component.
Publication Types:
* Clinical Trial
PMID: 12706228 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
73: Electromyogr Clin Neurophysiol. 1995
Jun-Jul;35(4):251-6. Related Articles, Links
Effects of visual and auditory stimuli on
median nerve somatosensory evoked potentials in man.
Okajima Y, Chino N, Takahashi M, Kimura A.
Department of Rehabilitation Medicine, Keio University School of
Medicine, Tokyo, Japan.
To demonstrate electrophysiological evidence of neural
connections of somatosensory with visual and auditory pathways,
interactions of median nerve somatosensory evoked potentials
(SEPs) with visual evoked potentials (VEPs) and auditory evoked
potentials (AEPs) were analyzed in 12 healthy subjects. In
Experiment I (SEP vs. VEP), three patterns of stimulation,
namely, electric stimulation of left median nerve, binocular LED
flash, and simultaneous electric and flash stimulation, were
applied with random interstimulus intervals of 2-4 sec until
more than 100 responses had been obtained and averaged for each
pattern of stimulation. Simultaneous electric and visual
responses were subtracted from arithmetical sums of SEPs and
VEPs to show interactions between somatosensory and visual
responses. In Experiment II (SEP vs. AEP), binaural
short-duration tone bursis instead of LED flashes were used in
the same manner as in Experiment I, and interactions between
somatosensory and auditory responses were analyzed. Results
indicated that the effects of both visual and auditory
interaction on SEPs were significant around 120-130 msec of
latency. In other words, cross-modal sensory interaction
occurred in the late phase of sensory processing.
PMID: 7555931 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
74: Neurosci Lett. 2000 Feb
4;279(3):153-6. Related Articles, Links
Different generators in human
temporal-parasylvian cortex account for subdural laser-evoked
potentials, auditory-evoked potentials, and event-related
potentials.
Lenz FA, Krauss G, Treede RD, Lee JL, Boatman D, Crone N,
Minahan R, Port J, Rios M.
Department of Neurosurgery, Johns Hopkins Hospital, Baltimore,
MD 21287-7713, USA. fal@pallidum.med.jhu.edu
In order to localize cortical areas mediating pain we now report
subdural cortical potentials evoked by auditory stimulation
(auditory-evoked potentials - AEPs) and by cutaneous stimulation
with a laser (laser-evoked potentials - LEPs). Stimulation with
the laser evokes a pure pain sensation by selective activation
of nociceptors. LEPs were maximal over the inferior aspect of
the central sulcus and had the same polarity on either side of
the sylvian fissure. AEPs were maximal posterior to the LEP
maximum and had opposite polarity on opposite sides of the
sylvian fissure, consistent with the location of a known
generator in the temporal operculum. Auditory P3 (event-related)
potentials were maximal over the temporal base. These findings
demonstrate that the LEP generator is not in secondary
somatosensory cortex on the parietal operculum and is different
from the P3 generator.
PMID: 10688052 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
75: Rev Neurol. 1998
Dec;27(160):955-63. Related Articles, Links
[Electrophysiological characteristics of
asymptomatic relatives of patients with type 2 spinocerebellar
ataxia]
[Article in Spanish]
Velazquez L, Medina EE.
Laboratorio de Neurofisiologia Clinica, Hospital Docente
Provincial Vladimir Ilich Lenin, Holguin, Cuba.
INTRODUCTION: Electrophysiological studies have been shown to be
useful in hereditary ataxia, but only a small number of patients
have been studied, and the duration of the illness, serial
studies and molecular definition have not been taken into
account. OBJECTIVE: We proposed, by means of
electrophysiological techniques, to characterize the functional
evolutionary state of the afferent and efferent systems in
asymptomatic relations of patients with type 2 spinocerebellar
ataxia (SCA2). Patients and methods. A 10 year longitudinal,
prospective study was made of 59 children of patients with SCA2.
The sequence included four studies: 1986, 1991, 1994 and 1996,
all with informed consent for the investigation. The control
group consisted of 108 volunteers. The electrophysiological
studies recorded were: conduction studies in peripheral nerves
and multimodal evoked potentials. For statistical analysis
multivariate methods were used with a confidence interval of 95%
(alpha = 0.05). RESULTS: Electrophysiological alterations were
observed even in the absence of clinical signs, such as reduced
amplitude of sensory potentials, morphological changes and
prolonged latency of the central components of somatosensory
evoked potentials, and of brain stem auditory evoked potentials,
whilst the visual evoked potentials remained normal. Of 79
relations studied during the 10 year investigation, 17 had
clinical signs and were considered to be patients with SCA2.
CONCLUSIONS: Four stages of the illness were defined: 'healthy',
presymptomatic, and patients with and without nerve conduction
block. These characterized the degenerative mechanisms of the
afferent and efferent systems of the relations of patients with
SCA2 who became ill themselves.
PMID: 9951012 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
76: Headache. 2001 Sep;41(8):792-7.
Related Articles, Links
Spectral analysis of visual potentials
evoked by pattern-reversal checkerboard in juvenile patients
with headache.
Marrelli A, Tozzi E, Porto C, Cimini N, Aloisi P, Valenti M.
Unita Operativa di Neurofisiopatologia, Ospedale S.
Salvatore-Coppito; Clinica Pediatrica, Universita di L'Aquila,
L'Aquila, Italy.
Changes in visual evoked potentials, mainly affecting the
amplitude of the major positive wave, are referred to by many
authors and are related to the pathophysiological basis of
primary headache. We performed both transient pattern-reversal
visual evoked potentials and spectral analysis by means of fast
Fourier transform of 8-Hz steady-state pattern-reversal visual
evoked potentials in 34 children affected with migraine (14 with
aura, 20 without aura), and compared them with 14 patients with
tension-type headache and 10 healthy subjects. The amplitude of
the response to the transient stimulation (P100) was higher and
the latency shorter in the patients with headache compared with
the controls, but the difference was not statistically
significant. The absolute power of the first harmonic (1F)
obtained by the spectral analysis of the steady-state
stimulation was increased in all the patients with headache
compared with the controls, and the increase was significant in
patients with migraine. These data seem to confirm the
hypothesis of abnormal processing of visual input in migraineurs
and could be interpreted as neurophysiological support for the
theory that different headache types are related conditions.
Furthermore, the spectral analysis of steady-state
pattern-reversal visual evoked potentials could be proposed as a
test to diagnose migraine.
PMID: 11576204 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
77: Muscle Nerve. 2000
Mar;23(3):321-35. Related Articles, Links
Electrophysiological studies of myoclonus.
Shibasaki H.
Departments of Neurology and Brain Pathophysiology, Kyoto
University School of Medicine, Shogoin, Sakyo, Kyoto, 606-8507
Japan.
As myoclonus is often associated with abnormally increased
excitability of cortical structures, electrophysiological
studies provide useful information for its diagnosis and
classification and about its generator mechanisms. The EEG-EMG
polygraph provides the most essential information about the
myoclonus of interest. Jerk-locked back averaging and evoked
potential studies combined with recording of the long latency,
long loop reflexes are useful to further investigate the
pathophysiology of myoclonus, especially that of cortical
myoclonus. A recent advance in magnetoencephalographic
techniques has contributed significantly to the elucidation of
some of the cortical mechanisms underlying myoclonus.
Elucidation of physiological mechanisms underlying myoclonus in
each individual patient is important for selecting the most
appropriate treatment of choice. Copyright 2000 American
Association of Electrodiagnostic Medicine.
Publication Types:
* Review
* Review Literature
PMID: 10679708 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
78: Klin Wochenschr. 1988;66 Suppl
14:1-10. Related Articles, Links
[Evoked potentials and intravenous
anesthetics]
[Article in German]
Kochs E, Schulte am Esch J.
Abteilung fur Anasthesiologie, Universitatskrankenhaus
Eppendorf, Hamburg.
In contrast to the electroencephalogram, which is a collection
of the spontaneous brain electrical potentials generated by the
cerebral cortex, evoked potentials are the electrical signals
generated by the nervous system in response to brief extrinsic
sensory stimuli. They can be used to establish objective
evidence of an abnormality when clinical signs and symptoms are
equivocal. Moreover they prove useful to define the anatomical
level of lesions in the afferent pathway tested. They have been
successfully applied during anesthesia and operations when
pathways amenable to evoked potential recording were at risk.
The most practical techniques in common intraoperative evoked
response monitoring involve stimulation of visual, auditory and
somatosensory pathways. As could be clearly demonstrated
alterations of evoked responses can not only be found with
diminished regional blood flow but in a graded manner depend on
the used anesthetics as well. The potential application of
evoked responses to monitor depth of anesthesia has been
demonstrated by several groups. In contrast to visual, auditory
and somatosensory cortical evoked potentials which show a large
inter- and intraindividual variance acoustical evoked brainstem
and somatosensory evoked subcortical potentials are very robust
under general anesthesia. Drug-induced effects on shape,
amplitude and latencies of evoked responses during balanced
anesthesia must be well documented in order to establish evoked
responses as sensitive indicators of systemic problems that may
threaten the viability of the central nervous system. There is
evidence that the effects on evoked responses during deep
anesthetic states can be mimicked by several life-threatening
conditions (e.g.: hypoxia, ischemia). This review describes the
effects of intravenously used anesthetic drugs on visual,
auditory and somatosensory evoked potentials and the alterations
in evoked responses by abnormal systemic conditions as seen
under hypotension, hypoxia, ischemia.
Publication Types:
* Review
* Review, Tutorial
PMID: 3292821 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
79: Brain. 2001 Nov;124(Pt
11):2310-8. Related Articles, Links
Increased visual after-effects following
pattern adaptation in migraine: a lack of intracortical
excitation?
Shepherd AJ.
School of Psychology, Birkbeck College, London, UK.
a.shepaerd@psychology.bbk.ac.uk
Much research on visual function in migraine has examined early
aspects of visual processing, often using detection or
discrimination measures and stimuli reported to trigger an
attack, e.g. striped patterns or flickering lights. Differences
between people with and without migraine have been attributed to
abnormal cortical processing in migraine, variously described by
interictal hyperexcitability, heightened responsiveness, a lack
of habituation and/or a lack of intra-cortical inhibition. Here,
two experiments are presented that explore a uniquely cortical
phenomenon, pattern or contrast adaptation, one using the motion
after-effect, one the tilt after-effect. Pattern adaptation
reflects specific interactions between groups of neurones and is
therefore ideally suited to address proposed models of cortical
function in migraine. These models lead to specific predictions
in an adaptation study: there should be smaller effects in
people with migraine than in people without. The results from
both adaptation experiments, however, revealed larger effects in
migraine sufferers than in headache-free control subjects. There
were no differences between migraine subgroups classified
according to the presence or absence of aura. These results are
discussed in terms of models of cortical function in migraine.
Publication Types:
* Clinical Trial
* Randomized Controlled Trial
PMID: 11673331 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
80: Neurolog. 2001 Sep;7(5):279-86.
Related Articles, Links
The pathophysiology of migraine.
Tepper SJ, Rapoport A, Sheftell F.
New England Center for Headache, Stamford, Connecticut,
Department of Neurology, Yale University School of Medicine, New
Haven, Connecticut, and Department of Psychiatry, New York
Medical College, New York, New York E-mail: sjtepper@aol.com
BACKGROUND: Migraine results from episodic changes in central
nervous system physiologic function in hyperexcitable brain
manifested by abnormal energy metabolism, lowered threshold for
phosphene generation, and increased contingent negative
variation. Human functional magnetic resonance imaging and
magnetoencepholography data strongly suggest that aura is caused
by cortical spreading depression. REVIEW SUMMARY: Brain
hyperexcitability may be caused by low magnesium levels,
mitochondrial abnormalities with abnormal phosphorylation of
adenosine 5'-diphosphate, a dysfunction related to nitric oxide,
or calcium channelopathy. Low magnesium can result in opening of
calcium channels, increased intracellular calcium, glutamate
release, and increased extracellular potassium, which may in
turn trigger cortical spreading depression. Mitochondrial
dysfunction has been suggested by a low phosphocreatine:Pi ratio
and a possible response by migraine patients to riboflavin
prophylaxis. Nitroglycerine administration results in a delayed
migraine-like headache in migraine patients but not in control
patients, and a nonspecific nitric oxide synthase inhibitor
aborted migraine at 2 hours in the majority of tested migraine
patients compared to controls. Many patients with familial
hemiplegic migraine have a missense mutation in the P/Q calcium
channel, so that this form of migraine, at least, is associated
with a demonstrable calcium channelopathy. CONCLUSIONS: The
generation of migraine occurs centrally in the brain stem,
sometimes preceded by cortical spreading depression and aura.
Activation of the trigeminovascular system stimulates
perivascular trigeminal sensory afferent nerves with release of
vasoactive neuropeptides, resulting in vasodilation and
transduction of central nociceptive information. There is then a
relay of pain impulses to central second- and third-order
neurons and activation of brain stem autonomic nuclei to induce
associated symptoms.
PMID: 12803669 [PubMed]
------------------------------------------------------------------------
81: Neuroscience.
2003;119(2):597-609. Related Articles, Links
Electrophysiological evidence for the
existence of a posterior cortical-prefrontal-basal forebrain
circuitry in modulating sensory responses in visual and
somatosensory rat cortical areas.
Golmayo L, Nunez A, Zaborszky L.
Department of Morphology, School of Medicine, Autonomous
University of Madrid, Madrid, Spain.
The prefrontal cortex (PFC) receives input from sensory
neocortical regions and sends projections to the basal forebrain
(BF). The present study tested the possibility that pathways
from sensory cortical regions via the PFC-BF and from the BF
back to specific sensory cortical areas could modulate sensory
responses. Two prefrontal areas that responded to stimulation of
the primary somatosensory and visual cortices were delineated:
an area encompassing the rostral part of the cingulate cortex
that responded to visual cortex stimulation, and a region
dorso-lateral to the first in the precentral-motor association
area that reacted to somatosensory cortex stimulation. Moreover,
BF neurons responded to PFC electrical stimulation. They were
located in the ventral pallidum, substantia innominata and the
horizontal limb of the diagonal-band areas. Of the responsive BF
neurons 42% reacted only to stimulation of
'visually-responsive,' 33% responded only to the
'somatosensory-responsive' prefrontal sites and the remaining
neurons reacted to both prefrontal cortical areas. The effect of
BF and PFC stimulations on somatosensory and visual-evoked
potentials was tested. BF stimulation increased the amplitude of
both sensory-evoked potentials. However, stimulation of the
'somatosensory-responsive' prefrontal area increased only
somatosensory-evoked potentials while 'visually-responsive'
prefrontal-area stimulation increased only visual-evoked
potentials. Atropine blocked both facilitatory effects.The
proposed cortico-prefronto-basalo-cortical circuitry may have an
important role in cortical plasticity and selective attention.
PMID: 12770572 [PubMed - in process]
------------------------------------------------------------------------
82: Crit Rev Oral Biol Med.
2000;11(1):57-91. Related Articles, Links
Acute and chronic craniofacial pain:
brainstem mechanisms of nociceptive transmission and
neuroplasticity, and their clinical correlates.
Sessle BJ.
Faculty of Dentistry, University of Toronto, Ontario, Canada.
This paper reviews the recent advances in knowledge of brainstem
mechanisms related to craniofacial pain. It also draws attention
to their clinical implications, and concludes with a brief
overview and suggestions for future research directions. It
first describes the general organizational features of the
trigeminal brainstem sensory nuclear complex (VBSNC), including
its input and output properties and intrinsic characteristics
that are commensurate with its strategic role as the major
brainstem relay of many types of somatosensory information
derived from the face and mouth. The VBSNC plays a crucial role
in craniofacial nociceptive transmission, as evidenced by
clinical, behavioral, morphological, and electrophysiological
data that have been especially derived from studies of the relay
of cutaneous nociceptive afferent inputs through the subnucleus
caudalis of the VBSNC. The recent literature, however, indicates
that some fundamental differences exist in the processing of
cutaneous vs. other craniofacial nociceptive inputs to the
VBSNC, and that rostral components of the VBSNC may also play
important roles in some of these processes. Modulatory
mechanisms are also highlighted, including the neurochemical
substrate by which nociceptive transmission in the VBSNC can be
modulated. In addition, the long-term consequences of peripheral
injury and inflammation and, in particular, the neuroplastic
changes that can be induced in the VBSNC are emphasized in view
of the likely role that central sensitization, as well as
peripheral sensitization, can play in acute and chronic pain.
The recent findings also provide new insights into craniofacial
pain behavior and are particularly relevant to many approaches
currently in use for the management of pain and to the
development of new diagnostic and therapeutic procedures aimed
at manipulating peripheral inputs and central processes
underlying nociceptive transmission and its control within the
VBSNC.
Publication Types:
* Review
* Review, Academic
PMID: 10682901 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
83: Brain. 1998 Feb;121 ( Pt
2):281-91. Related Articles, Links
Somatosensory-evoked blink response:
investigation of the physiological mechanisms.
Miwa H, Nohara C, Hotta M, Shimo Y, Amemiya K.
Department of Neurology, Juntendo University School of Medicine,
Tokyo, Japan.
The somatosensory-evoked blink response (SBR) is a newly
identified blink reflex elicited by electrical stimulation of
peripheral nerves. The present study was performed to
investigate the physiological mechanism underlying the SBR
elicited by median nerve stimulation in normal subjects. The
peripheral afferents responsible for the SBR included
low-threshold cutaneous fibres. In the SBR-positive subjects,
the late (R2) component of the blink reflex elicited by
supraorbital nerve stimulation and the SBR facilitated each
other when both responses were induced at the same time, but
they each caused long-lasting inhibition in the other when one
stimulus was given as a conditioning stimulus. The extent of
inhibition was correlated with the size of the preceding SBR. In
the SBR-negative subjects, simultaneous inhibition of R2 was
observed when median nerve stimulation was applied as a
conditioning stimulus. Brainstem excitability, as evaluated by
blink-reflex recovery studies, did not differ between
SBR-positive and SBR-negative subjects. Therefore, based on
anatomical and physiological findings, it appears that the
reflex pathways of the SBR and R2 converge within the brainstem
and compete with each other, presumably by presynaptic
inhibition at the premotor level, before entering the common
blink-reflex pathway. The influence of median nerve stimulation
upon tonic contraction of the orbicularis oculi muscle was
studied to detect the latent SBR. There was not only a
facilitatory period corresponding to the SBR but also an active
inhibitory period (exteroceptive suppression), suggesting that
the mechanism generating the SBR is not only influenced by
blink-reflex volleys but also by active exteroceptive
suppression. Thus, the SBR may appear as a result of integration
of facilitatory and inhibitory mechanisms within the brainstem.
PMID: 9549506 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
84: J Urol. 1991 Jul;146(1):118-23.
Related Articles, Links
Cortical evoked potentials by stimulation
of the vesicourethral junction: clinical value and
neurophysiological considerations.
Ganzer H, Madersbacher H, Rumpl E.
Division of Urology and Neurology, University Hospital,
Innsbruck, Austria.
In 21 healthy volunteers and 42 patients with either neurogenic
bladder dysfunction (24), partial peripheral denervation of the
bladder (12) or nonneurogenic bladder dysfunction (6)
scalp-derived evoked potentials after stimulation of the
vesicourethral junction (cortical evoked potentials) were
recorded. In addition, evoked potentials from the posterior
tibial nerve (tibial somatosensory evoked potentials) and from
the pudendal nerve (pudendal somatosensory evoked potentials)
were evaluated. The results obtained in normal subjects were
reproducible and comparable to those reported in previous
studies. Cortical evoked potentials of vesicourethral junction
consisted of a prominent negativity with a mean latency of 95
msec. Tibial and pudendal somatosensory evoked potentials were
similar and showed a typical W-shaped complex. In normal
subjects stimulation of the vesicourethral junction was
described as a stimulus-synchronous pulsation combined with a
continuous burning feeling and sometimes with a desire to void.
In 4 normal subjects no cortical evoked potentials of the
vesicourethral junction could be obtained because of a decreased
pain threshold. In regard to clinical value, the results
demonstrate that in patients with lesions of the central nervous
system (in the group with cauda equina and conus medullaris
lesions, and in the group with suprasacral spinal cord lesions)
the results of cortical evoked potentials of the vesicourethral
junction and pudendal somatosensory evoked potentials widely
correlate due to similar afferent nervous pathways within the
central nervous system. However, in patients with partial
peripheral denervation of the bladder with suspected additional
secondary local detrusor damage the results of cortical evoked
potentials obtained by stimulation of the vesicourethral
junction differ mostly from the results of somatosensory evoked
potentials obtained by stimulation of the pudendal nerve. The
pattern obtained (increased sensory and pain threshold, normal
cortical evoked potentials of the vesicourethral junction with
normal latencies and normal or increased amplitude) is
indicative of local detrusor damage. In 21 patients the ability
to detect cortical evoked potentials of the vesicourethral
junction was combined with the sensation of stimulus-synchronous
pulsation, whereas in the other 21 patients the absence of this
sensation during stimulation was combined with the absence of
cortical evoked potentials. On the other hand, no correlation
was found between the ability of obtaining cortical evoked
potentials of the vesicourethral junction and the
stimulus-induced sensation of pain and/or desire to
void.(ABSTRACT TRUNCATED AT 400 WORDS)
PMID: 2056569 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
85: J Neurol Sci. 1997 Feb
12;145(2):177-81. Related Articles, Links
Pattern reversal visual evoked potentials
in classic and common migraine.
Shibata K, Osawa M, Iwata M.
Department of Neurology, Neurological Institute, Tokyo Women's
Medical College, Japan.
Pattern reversal visual evoked potentials (PVEPs) to transient
checkerboard were recorded in 19 patients with migraine with
visual aura (i.e., classic migraine), 14 patients with migraine
without aura (i.e., common migraine) in the interictal period
and 43 normal subjects. Latencies and amplitudes of PVEPs in
each group were analyzed. In classic migraine patients, P100
amplitude was significantly higher than in normal subjects (p
< 0.01), whereas latencies of PVEPs did not significantly
differ. There were no significant differences between the common
migraine and normal subjects, nor within the classic and common
migraine groups in latencies and amplitudes of PVEP. Four
patients with classic migraine underwent PVEPs during or 1-2 h
immediately after their migraine attacks. Two of these patients
who underwent PVEPs 1.5-2 h after their attacks showed
abnormally increased PVEP amplitudes. These results suggest that
there are different pathophysiologies in the visual pathway
between classic and common migraine and furthermore, classic
migraine patients in interictal periods may have
hyperexcitability in the visual pathway and that the increased
amplitude of PVEPs after attacks may be due to cortical
spreading depression.
Publication Types:
* Clinical Trial
PMID: 9094046 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
86: J Neurol Neurosurg Psychiatry. 2000
Oct;69(4):507-11. Related Articles, Links
Long term decline of P100 amplitude in
migraine with aura.
Khalil NM, Legg NJ, Anderson DJ.
Department of Neurology, Imperial College School of Medicine,
Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
OBJECTIVES: To investigate visual function in migraine using
visual evoked potentials. METHODS: Electroretinograms (ERGs) and
visual evoked potentials (VEPs) to single flash (SF) and pattern
reversal (PR) stimuli were studied in 92 migraine subjects and
62 controls. RESULTS: In subjects with migraine, ERGs to single
flash were normal. Mean latencies of the P1 and P2 waves in the
SFVEP were increased at the occiput by 6% and 4% respectively,
but normal at the vertex. Mean latency of the P100 wave in the
PRVEP was increased by 5%. These increases were not related to
the presence or absence of an aura or to the duration of
migraine. P100 amplitude showed a more complex abnormality. It
was increased in migraine without aura by 23% compared with
controls, regardless of duration of migraine. In migraine with
aura it was similarly increased, by 23%, in cases of short
duration, but in addition it showed a sharp decline with
duration. In cases with a duration of 30 or more years it was
36% less than in cases of short duration, and 21% less than in
controls. CONCLUSIONS: Subjects with migraine have
constitutionally prolonged VEP latencies and increased P100
amplitude, but the latter declines to below normal in cases with
a long history of migraine with aura. This decline may reflect
subtle neuronal damage within the visual system from repeated
transient ischaemia experienced during the aura. Future
electrophysiological and other studies will need to be
controlled for duration of migraine history.
PMID: 10990512 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
87: Headache. 1997 Jun;37(6):383-5.
Related Articles, Links
Visual evoked potentials and serum
magnesium levels in juvenile migraine patients.
Aloisi P, Marrelli A, Porto C, Tozzi E, Cerone G.
Servizio di Neurofisiopatologia, University of L'Aquila, Italy.
Changes in visual evoked potentials and decreased intracellular
magnesium levels have been separately described in patients
affected by migraine both during the attacks and in the
interictal periods. An inverse correlation between increased
P100 amplitude and lowered serum magnesium levels was found in
children suffering from migraine with and without aura in a
headache-free period. A 20-day treatment with oral magnesium
pidolate seemed to normalize the magnesium balance in 90% of
patients. After treatment, the reduced P100 amplitude confirmed
the inverse correlation with the serum magnesium level. These
data seem to suggest the hypothesis that higher visual evoked
potential amplitude and low brain magnesium level can both be an
expression of neuronal hyperexcitability of the visual pathways
related to a lowered threshold for migraine attacks.
PMID: 9237412 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
88: Arch Neurol. 1997
May;54(5):619-24. Related Articles, Links
Influence of peripheral nerve stimulation
on human motor cortical excitability in patients with
ventrolateral thalamic lesion.
Hirashima F, Yokota T.
Department of Neurology, Tokyo Medical and Dental University,
Tokyo, Japan.
OBJECTIVE: To determine the peripheral afferent pathways that
influence the activities of the motor cortex by examining the
effects of peripheral nerve stimulation on motor cortical
excitability. PATIENTS AND METHODS: We examined 12 healthy
volunteers and 4 patients with localized brain lesions caused by
cerebrovascular attack. Of the 4 patients, 1 patient had pontine
infarction, including medial lemniscus, and severe sensory
deficit and 3 had small localized lesions in the lateral part of
the thalamus and neither sensory impairment nor abnormal N20
waves on somatosensory evoked potential recordings. Central
motor tract excitability was examined by measuring a change in
the motor evoked potential (MEP), using transcranial magnetic
stimulation of the motor cortex after peripheral nerve
stimulation at the wrist significantly increased MEP response in
the controls at long conditioning-test intervals of 28 to 60
milliseconds, as well as at short intervals of 0 to 6
milliseconds. A late MEP potentiation was not observed on the
affected side in all patients. CONCLUSIONS: The loss of late MEP
potentiation in patients with pontine and thalamic lesions
indicates that this potentiation is caused by the alternation of
the motor cortical excitability. Furthermore, the results in the
patients with thalamic lesions suggest that the lateral nuclei
of the thalamus, other than the ventral posterolateral nucleus
and probably including the ventrolateral nucleus, have an
important function in the processing of peripheral sensory input
for tuning motor cortical excitability.
PMID: 9152119 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
89: Rinsho Byori. 1995
Sep;43(9):965-70. Related Articles, Links
[Excitability of motor cortex with
transcranial magnetic double stimulation in the intact man]
[Article in Japanese]
Yoshino A, Yokota T.
Department of Medical Technology, Tokyo Medical and Dental
University.
To evaluate the excitability of central motor tract, we studied
a transcranial magnetic double stimulation with short
conditioning-test (C-T) interval of 1-10ms in eight normal
volunteers. In addition, H-reflex of the forearm muscle was used
to study the effect of the magnetic cortical conditioning
stimulus on alpha-motoneuron, and the test response evoked by
electrical cortical stimulation was also used to examine the
effect of the magnetic cortical conditioning stimulus. The
subthreshold conditioning and suprathreshold test stimuli were
applied, and compound muscle responses were recorded in the
relaxed abductor pollicis brevis muscle. There was a decrease of
the test response size by the conditioning stimulus at C-T
interval of 1-5ms. This attenuation was probably caused by
intracortical inhibition. Because the identical magnetic
cortical conditioning stimulus produced increase in H-reflex
size. Moreover, the test response evoked by electrical cortical
stimulus was not suppressed by the magnetic cortical
conditioning stimulus; whereas, response evoked by the magnetic
cortical test stimulus was suppressed at C-T intervals of 2ms.
With the technique of transcranial magnetic double stimulation,
therefore, it is possible to evaluate the inhibitory function in
the motor cortex. The technique may be of use for
pathophysiology, diagnosis and estimation of treatment in the
diseases.
Publication Types:
* Clinical Trial
PMID: 7474462 [PubMed - indexed for
MEDLINE]
------------------------------------------------------------------------
90: J Neurol Neurosurg Psychiatry. 1986
Nov;49(11):1280-7. Related Articles, Links
Visual evoked cortical potentials and
pattern electroretinograms in Parkinson's disease and control
subjects.
Nightingale S, Mitchell KW, Howe JW.
Parkinson's disease patients have been shown to have abnormal
visually evoked cortical potentials (VEPs) to pattern
stimulation. Whereas dopamine is not an important
neurotransmitter in the central visual pathways, the retina is
rich in dopamine and, together with previous animal and human
studies, this suggests that the abnormal VEPs in Parkinson's
disease patients may be due to a biochemical and
electrophysiological disorder in the retina. This hypothesis has
been examined by studying the VEPs and pattern electroretinogram
(PERG) of Parkinson's disease patients and matched control
subjects. The amplitudes of the cortical and retinal evoked
potentials were significantly reduced in Parkinson's disease
patients compared with the control subjects and this could not
be attributed to any particular feature of the disease or its
treatment. There was a significant relationship between the VEP
P100 latency and the PERG amplitude. Moreover for those subjects
in whom there was an interocular difference in both cortical and
retinal evoked potentials, the abnormality was more commonly
found in the potentials from the same eye. These findings
suggest that the abnormality of the VEP in Parkinson's disease
patients is, at least in part, secondary to an abnormality of
the retina itself.
PMID: 3794734 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
91: Headache. 1999
Jul-Aug;39(7):469-76. Related Articles, Links
The occipital cortex is hyperexcitable in
migraine: experimental evidence.
Aurora SK, Cao Y, Bowyer SM, Welch KM.
Department of Neurology, Henry Ford Health Sciences Center, 2799
West Grand Boulevard, Detroit, MI 48202-2689, USA.
OBJECTIVES: Threshold for generation of magnetophosphenes has
been reported to be lower in migraine. We compared the threshold
for eliciting phosphenes by transcranial magnetic stimulation
and the ability to visually trigger headache in a select group
of individuals with migraine with and without aura to normal
controls. METHODS: Transcranial magnetic stimulation was
performed using the Cadwell MES-10 stimulator. A circular coil,
9.5 cm in diameter, was applied to the occipital scalp (7 cm
above the inion). Stimulator intensity was increased in 10%
increments until subjects reported visual phenomena or 100%
intensity was reached. Stimulator intensity was then fine-tuned
to determine the threshold at which phosphenes were seen. In the
same subjects, visual stimulation was given in 3.0 T MRI and if
a headache occurred the response was recorded. RESULTS: Fifteen
subjects with migraine were compared to 8 controls. A
significant proportion of the migraineurs (86.7%) developed
phosphenes compared to the controls (25%) (P = .006). The
probability of triggering a headache was also higher in the
migraineurs (53%); no headache was triggered in the controls (P
= .019). A significant correlation was found between the
threshold for phosphenes on transcranial magnetic stimulation
and visually triggered headache (P = .002). When only migraine
was considered, there was again a significant trend (P = .084).
CONCLUSIONS: There is a difference in threshold for excitability
of occipital cortex in migraineurs and controls. The
hyperexcitable visual cortex in migraine is predisposed to
visually triggered headache.
PMID: 11279929 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
92: Nervenarzt. 2002 Apr;73(4):332-5.
Related Articles, Links
[Modulation of cortical excitability by
transcranial direct current stimulation]
[Article in German]
Nitsche MA, Liebetanz D, Tergau F, Paulus W.
Abteilung Klinische Neurophysiolgie, Georg-August-Universitat
Gottingen. mnitsch1@gwdg.de
Modulation of cerebral excitability is thought to be one
mechanism underlying the pharmacological treatment of
neuropsychiatric diseases such as epilepsy, depression, and
dystonia. Repetitive transcranial magnetic stimulation (rTMS)
has been tested for several years as a nonpharmacological,
noninvasive method of directly influencing patients' cortical
functions. We present an overview of the more easily performed
transcranial direct current stimulation (tDCS) with weak
current, which produces distinctly more pronounced changes in
excitability than rTMS. The basic underlying mechanism is a
shift in the resting membrane potential towards either hyper- or
depolarisation, depending on stimulation polarity. This in turn
leads to changes in the excitability of cortical neurons. Anodic
stimulation increases cortical excitability, while cathodic
stimulation decreases it. These changes persist after the end of
stimulation if the stimulation lasts long enough, i.e., at least
several minutes. The duration of this aftereffect can be
controlled through the duration and intensity of the
stimulation. Transcranial direct current stimulation essentially
allows a focal, selective, reversible, pain-free, and
noninvasive induction of changes in cortical excitability, the
therapeutic potential of which must be evaluated in clinical
studies, once possible risk factors have been assessed.
Publication Types:
* Review
* Review, Tutorial
PMID: 12040980 [PubMed - indexed for
MEDLINE]
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93: Acta Psiquiatr Psicol Am Lat. 1986
Mar;32(1):11-25. Related Articles, Links
[Electrophysiological contributions to the
study of attention]
[Article in Spanish]
Lolas F.
A selective review of electrophysiological studies of attention
and attentional behavior is presented. The emphasis is placed on
the contribution of cerebral event-related potentials (ERP)
(evoked potentials) to the clarification of major issues, such
as the role of peripheral versus central mechanisms and testing
of hypotheses regarding selective attention. A number of
clinical studies dealing mostly with diagnostic applications and
therapeutic trials is discussed. The difficulties of
interpretation and integration with other sources of knowledge
on behavioral physiology are briefly discussed.
PMID: 3751641 [PubMed - indexed for MEDLINE]
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94: Brain Dev. 1995
May-Jun;17(3):175-81. Related Articles, Links
Neurophysiological study in
Pelizaeus-Merzbacher disease.
Nezu A.
Department of Pediatrics, Yokohama City University, School of
Medicine, Japan.
The Neurophysiological characteristics of Pelizaeus-Marzbacher
disease (PMD) were studied in four Japanese patients aged
between 5 and 13 years. Pendular spontaneous nystagmus was
always recorded with a frequency between 2.5 and 4 Hz, and
abnormal saccades with an almost twofold prolongation in onset
time and 50% decrease in velocity were noted. Brainstem auditory
evoked potentials consistently demonstrated severely altered
waves II to V, following a normal wave I, despite normal hearing
acuity. Somatosensory evoked potentials (SEPs) were always
absent between brainstem components and early cortical
responses. Late cortical components of SEPs and visual evoked
potentials with significantly prolonged latencies were recorded
in the three younger cases having normal sensory and visual
acuity (N35 of SEP, 73.1 +/- 2.1 ms; N75 of VEP, 129.0 +/- 12.7
ms; mean +/- S.D.), while these peaks were absent in the oldest
case having the most severe handicap. In motor evoked potentials
(MEPs), R1 of blink reflex with significantly prolonged latency
(14.9 +/- 1.48ms) was always obtained, and no subsequent R2 was
elicited. Magnetic transcortical stimulation elicited no MEPs of
the thenar even in the facilitating condition on voluntary
contraction despite mild weakness of the thenar, while normal
MEPs were always elicited on cervical stimulation. These
electrophysiological findings were consistent with extensive
conduction slowing involving the brainstem to the cerebrum,
which seemed to be accompanied by conduction block in motor
systems rather than sensory systems. Although each of the
results was not specific, in combination they suggested the
characteristics of diffuse brain dysmyelination in PMD.
PMID: 7573756 [PubMed - indexed for MEDLINE]
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95: J Clin Neurophysiol. 2000
Mar;17(2):201-11. Related Articles, Links
Comment in:
* J Clin Neurophysiol. 2000 Mar;17(2):175-6.
Somatosensory, auditory, and visual evoked
magnetic fields in patients with brain diseases.
Nakasato N, Yoshimoto T.
Department of Neurosurgery, Tohoku University School of
Medicine, Sendai, Japan.
The features of somatosensory (SEFs), auditory (AEFs), and
visual evoked fields (VEFs) in healthy subjects and patients
with brain diseases provide the basis for clinical
investigations using magnetoencephalography (MEG). The SEFs
provide clinically useful information to identify the central
sulcus and somatotopic organization of the primary somatosensory
cortex. Localization accuracy of the SEFs can be tested by
cortical stimulation during surgery. Functional reorganization
suggested by SEF studies must be verified by other modalities.
The AEFs can localize the auditory cortex in the bilateral
temporal lobes. Separation of bilateral activities is much
clearer in AEFs than in auditory evoked potentials. Modulation
of the interhemispheric differences of latency, amplitude, and
source localization of AEFs can be used to evaluate auditory
function in patients with intracranial lesions. Pattern reversal
VEFs provide stable localization of the primary visual function.
Separation of bihemispherical activities is the advantage of
VEFs over visual evoked potentials. Investigation of VEFs
provides objective evaluation of visual field deficits such as
homonymous or bitemporal hemianopsia in patients with
intracranial lesions. Evoked magnetic fields can provide useful
diagnostic information. Such clinical findings, in turn,
provides the opportunity to test the source estimation accuracy
of MEG.
PMID: 10831111 [PubMed - indexed for MEDLINE]
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96: Muscle Nerve. 1996
Dec;19(12):1586-95. Related Articles, Links
Reduced brain stem excitability in
mitochondrial myopathy: evidence for early detection with blink
reflex habituation studies.
Koutroumanidis M, Papadimitriou A, Bouzas E, Avramidis T,
Papathanassopoulos P, Howard RS, Papapetropoulos T.
Department of Clinical Neurophysiology and Epilepsies, St
Thomas' Hospital, London, United Kingdom.
Blink reflex (BR) was studied in 17 patients with
histochemically and genetically confirmed mitochondrial myopathy
(MM). Fourteen patients had chronic progressive external
ophthalmoplegia (CPEO) associated with a mild to moderate
craniosomatic myopathy without any symptoms or signs of central
nervous system (CNS) involvement, 2 myoclonic epilepsy with
ragged red fibers syndrome, and 1 Kearns-Sayre syndrome. The
mean latencies of the early (R1) and late (R2) responses were
prolonged (P < 0.01 and P < 0.001, respectively), and the
corresponding amplitudes decreased (P < 0.001). Increased
habituation of the reflex was clearly observed in 10 out of 14
patients tested (71.4%), 9 of whom presented CPEO. These
findings suggest that the brain stem reticular network is in a
state of basal inhibition which is presumably due to a
subclinical impairment of the cerebral cellular metabolism.
Multimodal evoked potentials revealed abnormalities suggestive
of CNS involvement in 7 out of 17 patients (41.2%), 4 of whom
had CPEO. These observations document the validity of BR in
detecting clinically silent brain stem impairment in patients
with apparently pure MM and provide important clues for a
further understanding of the underlying pathophysiology.
PMID: 8941273 [PubMed - indexed for MEDLINE]
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97: Neurosci Lett. 2002 Nov
15;333(1):29-32. Related Articles, Links
Abnormal brain processing of cutaneous pain
in migraine patients during the attack.
de Tommaso M, Guido M, Libro G, Losito L, Sciruicchio V, Monetti
C, Puca F.
First Neurologic Clinic, University of Bari, Policlinico, Piazza
G Cesare 11, 70124 Bari, Italy. m.detommaso@neurol.uniba.it
We examined cutaneous pain thresholds using CO(2) laser stimuli
during migraine attacks, and defined the evoked cortical
potential characteristics. Ten patients without aura were
studied during attacks and for at least 72 h subsequently. Pain
stimuli were generated on the dorsum of both hands and the right
and left supraorbital zones, using pulses from a CO(2) laser.
Absolute latencies of scalp potentials were measured at the
highest peak of each response component, and the peak-to-peak
amplitudes of N2a-P2 components were recorded. Cutaneous pain
thresholds were significantly reduced on both the symptomatic
and non-symptomatic sides during the attack, in comparison with
the headache-free phase. The N2a-P2 complexes also increased in
amplitude during attacks in comparison with the pain-free side.
Thus, cutaneous hyperalgesia occurs during migraine attack, and
is subtended by central sensitization phenomena, probably
involving the cortex. Copyright 2002 Elsevier Science Ireland
Ltd.
PMID: 12401553 [PubMed - indexed for MEDLINE]
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98: Electroencephalogr Clin Neurophysiol.
1981 Oct;52(4):283-97. Related Articles, Links
Visual, auditory and somatosensory pathway
involvement in hereditary cerebellar ataxia, Friedreich's ataxia
and familial spastic paraplegia.
Pedersen L, Trojaborg W.
Pattern-reversal visual, auditory and somatosensory evoked
potentials were recorded from 11 patients with hereditary
cerebellar ataxia, 13 with familial spastic paraplegia and 7
with Friedreich's ataxia. In all the 31 patients the conduction
velocity along the median and tibial nerves to the level of the
spinal cord was normal. Five of the 7 patients with Friedreich's
ataxia had reduced sural nerve sensory potentials. There was
electrophysiological evidence of malfunction along one or
several pathways within the CNS in 8 of the 11 patients with
cerebellar ataxia, 4 of the 13 with familial spastic paraplegia,
and in all 7 cases of Friedreich's ataxia. The increase in
latency of visual, auditory and somatosensory evoked cortical
potentials is attributed to nerve fibre loss in the central
pathways with associated slowing of conduction.
PMID: 6169505 [PubMed - indexed for MEDLINE]
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99: J Neurol Sci. 1996
Oct;142(1-2):45-53. Related Articles, Links
Autosomal dominant cerebellar ataxia type
I: multimodal electrophysiological study and comparison between
SCA1 and SCA2 patients.
Perretti A, Santoro L, Lanzillo B, Filla A, De Michele G,
Barbieri F, Martino G, Ragno M, Cocozza S, Caruso G.
Department of Clinical Neurophysiology, Universita degli studi
di Napoli "Federico II", Italy.
A multimodal electrophysiological study was performed on 41
patients from 24 families with autosomal dominant cerebellar
ataxia type I (ADCA I). Upper- and lower-limb motor evoked
potentials (MEPs) to transcranial magnetic stimulation, median
and tibial nerve somatosensory evoked potentials (Mn and
Tn-SSEPs), orthodromic sensory (SCV) and motor conduction (MCV)
velocity along median and tibial nerve, brainstem auditory
evoked potentials (BAEPs), and visual evoked potentials (VEPs)
were examined. Molecular analysis showed 2 SCA1 families and 2
families linked to the SCA2 locus. A sural nerve biopsy was
performed in 5 patients. Brainstem damage of the auditory
pathway was observed in 79% of patients examined. VEP
abnormalities possibly of central origin were found in 52% of
patients. MEP and SSEP abnormalities were differently
distributed along the pathways examined: the longer the pathway,
the higher the occurrence and severity of impairment. Peripheral
dying-back neuropathy (confirmed by nerve bioptic data) was a
frequent finding (56%). A progressive degenerative process
involving first the longest tracts of the central motor and
central and peripheral branches of somatosensory pathways is
hypothesized in ADCA I. MEP abnormalities were more frequent in
SCA1, and the sensory-motor neuropathy was more severe in SCA2.
PMID: 8902719 [PubMed - indexed for MEDLINE]
------------------------------------------------------------------------
100: Headache. 1992 Jul;32(7):360-5.
Related Articles, Links
Bilateral occipital lobe infarction in
acute migraine: clinical, neurophysiological, and
neuroradiological study.
Ganji S, Williams W, Furlow J.
EEG and Evoked Potential Labs, Terrebonne General Medical
Center, Houma, Louisiana 70361.
A woman having common migraine attacks coincident with an
asymmetrical bilateral occipital lobe infarction that spared the
brainstem and cerebellum underwent these studies: serial
electroencephalography, brainstem auditory, visual and
somatosensory evoked potentials, magnetic resonance imaging of
the brain and cerebral arteriography. The patient's vision
improved greatly during a one-year follow-up. The absence of
risk factors for stroke suggested that migraine caused the
infarction in the posterior circulation network. The
pathophysiological mechanisms of stroke in migraine remains
speculative.
PMID: 1526769 [PubMed - indexed for MEDLINE]
