Migraine & Headache
Treatment of migraine with pulsing electromagnetic fields
Initial exploration of pulsing electromagnetic fields for treatment of migraine
Influence of pineal gland on migraines & headaches and treatment with magnetic
fields
Effect of pulsating electromagnetic field therapy on multiple sclerosis and migraine
Magnetic field associated with spreading depression: a model for the detection
of migraine
Use of a pulsating magnetic field in neuropsychiatry patients with long-term
headache
---------------------------------------------------------
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.
The effect of exposure to pulsing electromagnetic fields on migraine activity
was evaluated by having 42 subjects (34 women and 8 men), who met the International
Headache Society's criteria for migraine, participate in a double-blind, placebo-controlled
study. Each subject kept a 1-month, pretreatment, baseline log of headache
activity prior to being randomized to having either actual or placebo pulsing
electromagnetic fields applied to their inner thighs for 1 hour per day, 5
days per week, for 2 weeks. After exposure, all subjects kept the log for at
least 1 follow-up month. During the first month of follow-up, 73% of those
receiving actual exposure reported decreased headaches (45% good decrease,
14% excellent decrease) compared to half of those receiving the placebo (15%
worse, 20% good, 0% excellent). Ten of the 22 subjects who had actual exposure
received 2 additional weeks of actual exposure after their initial 1-month
follow-up. All showed decreased headache activity (50% good, 38% excellent).
Thirteen subjects from the actual exposure group elected not to receive additional
exposure. Twelve of them showed decreased headache activity by the second month
(29% good, 43% excellent). Eight of the subjects in the placebo group elected
to receive 2 weeks of actual exposure after the initial 1-month follow-up with
75% showing decreased headache activity (38% good, 38% excellent). In conclusion,
exposure of the inner thighs to pulsing electromagnetic fields for at least
3 weeks is an effective, short-term intervention for migraine, but not tension
headaches.
Headache. 1999 Sep;39(8):567-75.
Headache
The administration of a pulsed magnetic field for less than one hour to headache
patients produced significant beneficial effects, as shown in patient reports,
as well as EEG activity. Acute migraine patient, who was successfully treated
with external magnetic fields.
107 patients suffering from headaches of varying causes. Treatment consisted
of the Nao-Hu, Bai-Huei, and Hua-Chai acupuncture points being exposed to
5.6- and 4.9-mm wavelengths via the use of "Yav'-1-5.6" or "Electronka-KVCh" devices,
respectively. Exposure lasted up to 60 minutes per day over a course of 10
days. All patients experienced positive results following 3-5 exposures.
After one year, 48 percent of patients remained free of headaches, with a
significant decrease in another 41 percent.
Pulsed electromagnetic fields (20 minutes per day for 15 days) in the treatment
of patients suffering from chronic headaches. Results indicated the treatment
to be most effective in patients suffering from tension headaches, with 88
percent of such patients reporting positive results. Beneficial results were
also experienced patients suffering from migraines (60 percent), cervical
migraines (68 percent), and psychogenic headaches (60 percent).
O. Grunner, et al., "Cerebral Use of a Pulsating Magnetic Field
in Neuropsychiatry Patients with Long-term Headache,"
R. Sandyk, "The Influence of the Pineal Gland on Migraine and Cluster
Headaches and Effects of Treatment with picoTesla Magnetic Fields," B.M.
Popov & T.A. Al'shanskaya, "Use of Traditional and Non-traditional
Methods in the Treatment of Headache," Millimeter Waves in Medicine and
Biology. A. Prusinski, et al., "Pulsating Electromagnetic Field in the
Therapy of Headache,"
Magnetic Fields for Migraines? Recent Studies Show Promise, New Study Underway
by Martha Lappin, PhD, Alternative Health Care Research, Inc.
Migraine headaches plague millions of people in the United States. Stewart
et al. (1992) report that 18% of the women and 6% of the men in this country
experience migraines every year. Furthermore, 4.5 million individuals have
one or more disabling attacks a month. The large majority of migraine sufferers
are in their prime productive years, and the social as well as the treatment
costs are enormous.
Conventional, Pharmacological Treatments
Until recently, migraines were treated primarily with analgesics. However,
using drugs to dull the pain of recurrent headaches is not a satisfactory long-term
solution. Relying on pain killers month after month creates a high potential
for dependence, habituation, and rebound headaches, even with over-the-counter
analgesics. A second approach is to take medications to abort the attack (e.g.,
Imitrex, Zomig). Although these drugs are effective for some, the cost is high
and the relief is often temporary - 40% to 78% of patients experience a recurrence
of the headache within 24 hours (Peroutka, 1998).
The third treatment approach, preventing migraine attacks from occurring in
the first place, has also proved unsatisfactory. Beta blockers, antidepressants,
calcium channel blockers, and methysergide, and Depakote have all been used
for this purpose, but evidence regarding their effectiveness is mixed, and
all have side effects or serious contraindications.
There is a clear need for safe therapies that can prevent or reduce the frequency
of migraines among chronic sufferers. Discouraged with conventional pharmacological
treatments, many migraine sufferers have turned to complementary and alternative
therapies. Biofeedback, meditation, visualization, transcranial electrical
stimulation, feverfew, and acupuncture have all been reported to be effective
for some migraine patients. Another option that is generating interest is stimulation
with pulsed electromagnetic fields. Research in this area is described below.
Pulsed Electromagnetic Fields
Pulsed electromagnetic fields (EMFs) vary in terms of frequency (measured
in Hz or oscillations per second) and strength (measured in gauss or tesla).
Preliminary studies have examined the effects of both high strength, high frequency
stimulation, and low strength, low frequency stimulation on migraines. Researchers
at a Veterans Hospital near Seattle, looked at the former. In both a small
open study and a small double-blind, placebo controlled study, subjects experienced
a marked reduction in migraine frequency (e.g., from 3 or 4 per week to less
than one per week) following treatments with high powered, high frequency pulsed
EMFs (Sherman, Robson, & Marden, 1998).
Positive results have also been obtained in studies examining the
effects of much weaker fields pulsed at extremely low frequencies. Young
(1993), for
example, tracked 54 migraine sufferers for three months after they received
a device that emitted extremely low frequency (3 to 12 Hz) EMFs no stronger
that the earth’s magnetic field. The average number of migraines dropped
by half, from 1.2 to .6 per week, once subjects started wearing the pulsing
EMF devices.
Several years later, researchers asked migraine patients who had received
similar devices in clinics in Great Britain (n=264) to evaluate the effectiveness
of the therapy (Lappin, 1995). Among those with the worst problems prior to
treatment 60% said they improved by 5 or more points on a 10 point scale, and
over one fourth of the respondents indicated that they were virtually migraine
free after using the device. Only 15% failed to improve at all. Comparable
results were reported for those with only moderately severe problems prior
to treatment. A much smaller study (n=20) of patients treated in Canada showed
a similar pattern of results - 25% found the treatment to be extremely effective
and another 45% indicated that it was moderately to very effective (Lappin,
1999).
These studies are not conclusive because we cannot rule out placebo effects
and response bias as explanations for the positive results. However, the findings
certainly indicate that additional research is warranted. Although we do not
know exactly how electromagnetic therapies work, basic researchers have shown
that pulsed EMFs affect some of the neurotransmitters and hormones involved
in the pathogenesis of migraines.
A New Study
A more scientifically rigorous study of weak, extremely low frequency EMFs
is just getting underway in northern Virginia. Funded by the National Center
for Complementary and Alternative Medicine (NCCAM) at the National Institutes
of Health (NIH), this research will be a randomized, double-blind, placebo
controlled trial. Migraine sufferers who are interested in participating can
call the number listed below for additional information. Participants must
be able to travel to a research site in northern Virginia five times over the
course of the five month study, and suffer an average of two migraines a month.
Subjects will not be required to discontinue any migraine medications they
are currently taking. All subjects in the placebo group will be offered a chance
to try the real treatment at the end of the formal study.
For more information e-mail MPrunchak@aol.com
Lappin MS. Research on the Utility of the Enermed Device as a Treatment for
Migraines. Research Report # 1, April 1995. Vancouver, BC: Energy Medicine
Developments (North America) Inc.
Lappin MS. 1999 Enermed Patient Survey Results. Research Report # 4, November,
1999. Vancouver, BC: Energy Medicine Developments (North America) Inc.
Peroutka SJ. Beyond monotherapy: Rational polytherapy in migraine. Headache,
1998, 38:18-22.
Sherman RA, Robson L, Marden LA. Initial exploration of pulsing electromagnetic
fields for treatment of migraine. Headache, 1998,
Stewart WF, Lipton RB, Celentano DD, et al. Prevalence of migraine headache
in the United States: Relation to age, income, race and other sociodemographic
factors. JAMA, 1992, 267:64-69.
Young S. Pilot study concerning the effects of extremely low frequency electromagnetic
energy on migraine. Int J Alt Complement Med, October, 1993.
Headache - Migraine
R. Sandyk: 'The Influence of the Pineal Gland on Migraine and Cluster Headaches
and Effects of Treatment with Picotesla Magnetic Fields' International Journal
of Neurosci. 67 (1-4), November-December 1992, pp. 145-171. - This article
reports on a migraine patient with acute attacks who was treated and cured
with external pulsating electromagnetic fields.
Prusinki et. al.: PEMF in the Treatment of Headaches, Hungarian Symposium on
Magnetic Therapy, 2nd Symposium, May 16-17, 1987. - This study investigates
the effect of PEMF on Patients suffering from chronic headaches. Positive results
were achieved in 88% of the cases with stress headaches, in more than 60% of
those with classical migraines and in 68% of those with so-called cervical
migraines.
B.M. Popov, T.A Al'Shanskaya: 'Use of Traditional and Non-traditional Methods
in the Treatment of Headache," Millimetre Waves in Medicine and Biology.
Digest of Papers of the 11th Russian Symposium with International Participation,
21-24 April 1997, Zvenigoro, Moscow Region, pp. 68f - This study investigates
the effect of therapy in the treatment of 107 patients who suffered from headaches
of a wide variety of causes. Acupuncture points were stimulated electromagnetically.
More than 80% of the patients had a positive experience.
J. Gicze, A. Guseo: 'Treatment of Headache [with] Pulsating Electromagnetic
Field, a Preliminary Report,' Hungarian Symposium on Magnetic therapy, 2nd
Symposium, May 1987.- This study shows the efficacy of PEMF in prophylactic
and therapeutic use on migraine patients.
Pelka, Jaenicke, Gruenwald. Uni. Bundeswehr München Germany.
This double blind, placebo-controlled study assessed the efficacy of 4 weeks
of impulse magnetic-field therapy (16 Hz, 5 Mikrotesla), delivered through
a small device, for different types of headache and migraine. Eighty-two patients
were randomly assigned to receive either active treatment or placebo (n = 41
each) and were characterized according to one of seven diagnoses (migraine,
migraine combined with tension, tension, cluster, weather-related, posttraumatic,
or other). Efficacy was assessed in terms of duration, severity, and frequency
of migraine and headache attacks, as well as ability to concentrate. Data for
77 patients were analysed. In the active-treatment group, all assessed criteria
were significantly improved at the end of the study (P < .0001 vs baseline
and placebo). Seventy-six percent of active-treatment patients experienced
clear or very clear relief of their complaints. Only 1 placebo-patient (2.5%)
felt some relief; 8% noted slight and 2% reported significant worsening of
symptoms. No side effects were noted. PMID: 11571822 PubMed
Entrez-PubMed is a search and retrieval system that integrates information
from databases at U.S. National Center of Biotechnology Information; the
National Library of Medicine and the National Institutes of Health. see extensive
research links below.
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.
1: Ambrosini A, Schoenen J. Related Articles, Links
The electrophysiology of migraine.
Curr Opin Neurol. 2003 Jun;16(3):327-31. Review.
PMID: 12858069 [PubMed - indexed for MEDLINE]
2: Schoenen J, Ambrosini A, Sandor PS, Maertens de Noordhout A. Related Articles,
Links
Evoked potentials and transcranial magnetic stimulation in migraine: published
data and viewpoint on their pathophysiologic significance.
Clin Neurophysiol. 2003 Jun;114(6):955-72. Review.
PMID: 12804664 [PubMed - indexed for MEDLINE]
3: Bohotin V, Fumal A, Vandenheede M, Bohotin C, Schoenen J. Related Articles,
Links
Excitability of visual V1-V2 and motor cortices to single transcranial magnetic
stimuli in migraine: a reappraisal using a figure-of-eight coil.
Cephalalgia. 2003 May;23(4):264-70.
PMID: 12716343 [PubMed - indexed for MEDLINE]
4: Aurora SK, Welch KM, Al-Sayed F. Related Articles, Links
The threshold for phosphenes is lower in migraine.
Cephalalgia. 2003 May;23(4):258-63.
PMID: 12716342 [PubMed - indexed for MEDLINE]
5: Ambrosini A, de Noordhout AM, Sandor PS, Schoenen J. Related Articles, Links
Electrophysiological studies in migraine: a comprehensive review of their interest
and limitations.
Cephalalgia. 2003;23 Suppl 1:13-31. Review.
PMID: 12699456 [PubMed - indexed for MEDLINE]
6: Mulleners W, Chronicle E, Vredeveld J, Koehler P. Related Articles, Links
Visual cortex excitability in migraine before and after valproate prophylaxis:
a pilot study using TMS.
Headache. 2003 Mar;43(3):304.
PMID: 12603670 [PubMed - as supplied by publisher]
7: Ozturk V, Cakmur R, Donmez B, Yener GG, Kursad F, Idiman F. Related Articles,
Links
Comparison of cortical excitability in chronic migraine (transformed migraine)
and migraine without aura. A transcranial magnetic stimulation study.
J Neurol. 2002 Sep;249(9):1268-71.
PMID: 12242552 [PubMed - indexed for MEDLINE]
8: Brighina F, Piazza A, Daniele O, Fierro B. Related Articles, Links
Modulation of visual cortical excitability in migraine with aura: effects of
1 Hz repetitive transcranial magnetic stimulation.
Exp Brain Res. 2002 Jul;145(2):177-81. Epub 2002 May 09.
PMID: 12110957 [PubMed - indexed for MEDLINE]
9: Battelli L, Black KR, Wray SH. Related Articles, Links
Transcranial magnetic stimulation of visual area V5 in migraine.
Neurology. 2002 Apr 9;58(7):1066-9.
PMID: 11940694 [PubMed - indexed for MEDLINE]
10: Bohotin V, Fumal A, Vandenheede M, Gerard P, Bohotin C, Maertens de Noordhout
A, Schoenen J. Related Articles, Links
Effects of repetitive transcranial magnetic stimulation on visual evoked potentials
in migraine.
Brain. 2002 Apr;125(Pt 4):912-22.
PMID: 11912123 [PubMed - indexed for MEDLINE]
11: Mulleners WM, Chronicle EP, Vredeveld JW, Koehler PJ. Related Articles,
Links
Visual cortex excitability in migraine before and after valproate prophylaxis:
a pilot study using TMS.
Eur J Neurol. 2002 Jan;9(1):35-40.
PMID: 11784374 [PubMed - indexed for MEDLINE]
12: Mulleners WM, Chronicle EP, Palmer JE, Koehler PJ, Vredeveld JW. Related
Articles, Links
Visual cortex excitability in migraine with and without aura.
Headache. 2001 Jun;41(6):565-72.
PMID: 11437892 [PubMed - indexed for MEDLINE]
13: Aurora SK, Cao Y, Bowyer SM, Welch KM. Related Articles, Links
The occipital cortex is hyperexcitable in migraine: experimental evidence.
Headache. 1999 Jul-Aug;39(7):469-76.
PMID: 11279929 [PubMed - indexed for MEDLINE]
14: Mulleners WM, Chronicle EP, Palmer JE, Koehler PJ, Vredeveld JW. Related
Articles, Links
Suppression of perception in migraine: evidence for reduced inhibition in the
visual cortex.
Neurology. 2001 Jan 23;56(2):178-83.
PMID: 11160952 [PubMed - indexed for MEDLINE]
15: Cutrer FM, O'Donnell A, Sanchez del Rio M. Related Articles, Links
Functional neuroimaging: enhanced understanding of migraine pathophysiology.
Neurology. 2000;55(9 Suppl 2):S36-45. Review.
PMID: 11089518 [PubMed - indexed for MEDLINE]
16: Werhahn KJ, Wiseman K, Herzog J, Forderreuther S, Dichgans M, Straube A.
Related Articles, Links
Motor cortex excitability in patients with migraine with aura and hemiplegic
migraine.
Cephalalgia. 2000 Feb;20(1):45-50.
PMID: 10817446 [PubMed - indexed for MEDLINE]
17: Afra J, Ambrosini A, Genicot R, Albert A, Schoenen J. Related Articles,
Links
Influence of colors on habituation of visual evoked potentials in patients
with migraine with aura and in healthy volunteers.
Headache. 2000 Jan;40(1):36-40.
PMID: 10759901 [PubMed - indexed for MEDLINE]
18: Maertens de Noordhout A, Schoenen J. Related Articles, Links
Transcranial magnetic stimulation in migraine.
Electroencephalogr Clin Neurophysiol Suppl. 1999;51:260-4. Review. No abstract
available.
PMID: 10590958 [PubMed - indexed for MEDLINE]
19: Aurora SK, al-Sayeed F, Welch KM. Related Articles, Links
The cortical silent period is shortened in migraine with aura.
Cephalalgia. 1999 Oct;19(8):708-12.
PMID: 10570724 [PubMed - indexed for MEDLINE]
20: Cutrer FM, O'Donnell A. Related Articles, Links
Recent advances in functional neuroimaging.
Curr Opin Neurol. 1999 Jun;12(3):255-9. Review.
PMID: 10499170 [PubMed - indexed for MEDLINE]
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]
------------------------------------------------------------------------
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]
------------------------------------------------------------------------
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]
------------------------------------------------------------------------
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]
------------------------------------------------------------------------
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]
------------------------------------------------------------------------
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]
------------------------------------------------------------------------
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]
------------------------------------------------------------------------
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]
|