Pattern-Shift Visual Evoked Responses in Cluster Headache

SYNOPSIS
Visual evoked responses (VERs) elicited with two different sizes of checkerboard patterns were obtained from 10 male cluster headache patients and their age-matched controls. Full-and half-field stimulus presentations produced no substantial differences between the subject groups for any of the major component latencies or amplitudes (N75, P100, N145). No differences were obtained for either checkerboard size between the groups or when the specific side of headache pain was assessed separately. The results are discussed in terms of previous VER headache studies.     

Visual Evoked Potentials and Background EEG Activity in Migraine

To investigate whether quantification of the background EEG during a visual evoked potential (VEP) study is of value for the diagnosis of migraine we studied 8 unmedicated migraineurs between attacks, and 10 age-matched controls. Three paradigms were used: the first two concerned pattern-reversal VEPs with different analysis times (500 and 1500 ms), and in the third paradigm the pattern did not reverse. Power spectra were calculated for individual responses, and the delta, theta, alpha and beta areas of the averaged spectra were noted as indicators of background reactivity. Alpha and beta powers were consistently but not significantly higher in the migraine group. The difference was too small to be of value as a diagnostic test. Alpha power was (not significantly) lower in the presence of photic stimulation than in its absence. As this was the case in both groups photic stimulation does not explain the higher alpha powers in the migraine group. We conclude that EEG background activity during the VEP does not distinguish reliably between migraineurs and controls.     

Pattern-reversal Visual Evoked Potentials and EEG Correlations in Common Migraine Patients

SYNOPSIS
22 migraine patients, aged between 17 and 60 years (7 males and 15 females) were studied through the method of Visual Evoked Potentials (VEP). The control group consisted of an equal number of healthy subjects, comparable for age and sex. Correlations between the results obtained with VEP and those reported by traditional EEG methods were investigated. As found by other authors, VEP's did not point to any significant difference in common migraine as compared to a control group of healthy subject.
Unlike other authors we found the presence of mildly abnormal EEG elements in only 19% of patients.     

Visual Evoked Potentials in Menstrual Migraine

SYNOPSIS
Visual evoked potentials (VEP) were recorded and plasma estrogen, progesterone, FSH and LH hormones were determined in a group of patients with menstrual migraine and in healthy controls. Consistent differences from controls were found in the VEPs of migraine patients, justifying the use of VEP recording as a method of investigating the neurophysiology of migraine. The VEPs were not dependent on the hormonal cycle, except for responses to flashes 10/sec which in healthy persons were higher in the luteal phase. This was less clear in migraine patients. Some of the patients showed strong asymmetrical VEP distortion, which was always transient; follow-up revealed later normalisation. The transient and asymmetrical VEP distortion seemed to relate to the asymmetrical symptoms of migraine, but a direct connection between the two was not established.     

Visual Evoked Potential in Patients with Migraine

SYNOPSIS
Using pattern reversal stimuli, visual evoked potentials (VEP) were measured between attacks in 40 (6 classic and 34 common) migraine sufferers, and in 20 control subjects. While there were no statistically significant differences between the groups in mean P wave latency or in mean P wave amplitude, there were some intriguing individual findings in some of the migraine patients. Nine had P wave latencies more than 2 SD above the control mean; 6 had more than 2 SD increases above control in P wave amplitude; 3 had simultaneous increases in both latencies and amplitudes. In almost all the cases with these unusual values, the tracing had been done close in time to a migraine attack.     

Migraine Patients Exhibit Abnormalities in the Visual Evoked Potential

SYNOPSIS
An experiment is described which compared visual evoked potential (VEP) amplitudes and latencies in normal subjects and migraine patients. Several VEP abnormalities were found: at vertex and to a lesser extent at temporal sites, P100-N120 amplitudes were larger in patients; at vertex and temporal sites N120 amplitudes were larger in patients; at temporal sites patients had larger N120-P200 amplitudes but smaller P100 amplitudes. Peak latencies of the VEP were also found to be abnormal in patients. At vertex, patients had delayed N120 peak latencies while at temporal sites delays were found in the P200 latencies. Patients were subdivided according to side of headache. Right-sided headache patients showed larger temporal P100 amplitudes and larger left temporal P100-N120 amplitudes than bilateral headache patients.     

Visual Evoked Potentials and Serum Magnesium Levels in Juvenile Migraine Patients

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.     

Transient Asymmetries of Steady-State Visual Evoked Potentials in Classic Migraine

Unilateral abnormalities in the regional cerebral blood flow (rCBF) and visual evoked potentials (VEPs) during the visual aura of classic migraine have been reported. On the other hand, there are only few observations suggesting unilateral abnormality of neural function during the headache-free period. An experiment is described in which the symmetries of steady state VEPs (SVEPs) are compared in healthy subjects and classic migraineurs in the headache-free interval. In the patients an increased number of strong short-lasting interhemispheric asymmetries was found. In the serial recordings performed, pathologic recordings were obtained intermittently, usually with complete normalisation in the following session. The incidence of abnormalities was relatively independent of the interval between the recording and attack, except for the next few hours. The findings may be related to instability of occipital cortical function in classic migraine.     

Pattern Reversal Visual Evoked Potentials (VEP-PR) in Migraine Subjects With Visual Aura

Twenty patients with migraine with visual aura, aged 19 to 55 years (2 men and 18 women) were studied by the method of Visual Evoked Potentials (VEP). The control group consisted of an equal number of healthy subjects, comparable for age and sex. The most important finding in our study is that migraine patients with visual prodromata have a significantly longer P100 latency than the subjects of control group. These modifications of the VEP-PR could indicate, as other investigators have pointed out, that there are some special metabolic conditions and abnormalities of neuromediators during and between attacks.     

Basilar Artery Migraine: EEG and Evoked Potential Patterns During Acute Stage

SYNOPSIS
Electroencephalographic and evoked potential studies were done during the ictal phase of migraine in a 22-year-old woman with basilar artery migraine. Prominent posterior slowing was seen in the EEG pattern during the symptomatic period. Clinical improvement coincided with the reversal of abnormality in the EEG tracing. The findings from the multimodality evoked potentials were within normal limits.     

A Diagnostic Test for Migraine Using the Visual Evoked Potential

SYNOPSIS
Traditionally the diagnosis of migraine has been made by clinical history, examination and investigation to exclude other ophthalmological and neurological diseases. To date there has been no simple objective test for the diagnosis of migraine on an individual basis. Patients were subjected to both flash and pattern light stimuli, and measurements were made from the resultant visual evoked potential (VEP) charted as a waveform. Calculations based on the parameters of the waveforms produced a Coefficient which correlated well with the medical diagnosis. This study demonstrates that electro-diagnostic methods can be utilised to provide a fast, reliable and accurate diagnosis for migraine on an individual basis, and which will also differentiate between the Common and Classical varieties.     

A Multivariate Analysis of Evoked Responses in EEG and MEG Data

This paper presents a multivariate analysis of evoked responses and their spatiotemporal dynamics as measured with electro- or magnetoencephalography. This analysis uses standard techniques (ManCova) to make possible statistical inference about differential responses, after the data have been transformed using singular value decomposition. The generality of this approach is limited only by the assumptions implicit in the general linear model and can range from simple analyses like Hotelling'sT²test (in comparing evoked responses among different conditions) to complex analyses of a multivariate regression type (e.g., characterizing the response components associated with a behavioral or psychophysical parameter). To illustrate the technique we have characterized time-dependent changes (both within and between trials) in magnetic fields, evoked by self-paced movements. Our illustrative analysis showed that movement-evoked components were less prone to adaptation than premovement components, suggesting that functionally distinct (preparatory and early executive) biomagnetic signals show differential adaptation.     

Auditory Brainstem Evoked Potentials in Patients with Migraine

SYNOPSIS
Auditory brainstem evoked potentials (ABEP's) using the routine 10 per second click rate, and also a 55 persecond stimulus rate, were studied in 17 migraine patients between and during attacks, and in 20 normal subjects.Only in the "migraine during attack" group did the increased stimulus rate change the ABEP's. Similar changeswith increased stimulus rates may be seen in situations of ischemic synaptic dysfunction. Thus, our data supporta vascular pathogenesis of migraine.     

EEG Features in Basilar Artery Migraine

SYNOPSIS
Standard and 24-hour ambulatory cassette electroencephalograms (EEG) were performed in 51 female patients with basilar artery migraine (BAM). None of the patients were known epileptics. The group age average was 29 years. Anomalies were detected in 9 patients (17.6%) Two exhibited paroxysmal specific (i.e., epileptogenic) and 7 paroxysmal non-specific abnormalities. Studies during the symptomatic period on 7 patients were normal, and in one adolescent photoparoxysmal discharges were present. Her headaches persisted despite the suppression of EEG photoparoxysmal activity with valproate and carbamazepine; conversely, she was clinically improved with propranolol. EEG abnormalities occurred in the minority of adults afflicted with BAM. The presence of ictal or interictal abnormalities is not an absolute indication for antiepileptic therapy although these agents may, occasionally, be efficacious in the treatment of migraine, independent of associated EEG disturbances.     

EEG Markers of Migraine in Children and Adults

SYNOPSIS
EEG markers of migraine in childhood were characterized using computer techniques for harmonic analysis of the EEG during photic stimulation. We examined values of coherence, power in the alpha range, response to photic stimulation and attenuation of power in the alpha range during photic driving. With these data, we were able to discriminate 12 of 13 children with migraine from age-matched controls. We compared our results to previous data with adults and found many properties in the spectral analyses common to both children and adults, but also found a small set of properties unique to children.     

Basilar Migraine With Severe EEG Abnormalities

SYNOPSIS
We report a patient suffering from a series of attacks fulfilling the criteria of basilar migraine. During the attack there was no normal EEG background pattern and the EEG showed predominantly delta activity. After the attack the EEG returned to (nearly) normal in a very short time. Up to now no such EEG findings have been reported in basilar migraine.     

Brainstem Auditory Evoked Potentials (BAEPs) in Childhood Migraine

SYNOPSIS
Brainstem auditory evoked potentials (BAEPs) were recorded in pain-free periods in 28 children suffering from migraine (23 common and 5 classic). They were without medication for at least one month before there cording session. The results were compared with a group of 10 normal subjects matched for sex and age. We found no significant differences between the migraine group and the control subjects; when analyzing separately the classic and common form, two groups either with more or less than 5 years of history of migraine or with and without nausea and/or vomiting, similar results were obtained. Our data suggest that in migrainous children conduction in the auditory pathway at the brainstem level is not significantly different from controls.     

Characteristics of Migraine Visual Aura

Visual auras (VAs) of 100 patients with migraine with aura were studied by questionnaire. Visual auras accompanied the patients' first headache (HA) in 39% of patients. Only 19% had VAs with every attack. Patients with VAs over the entire HA history had a high frequency (greater than 50%) of attacks with VA; patients with VA during only part of the HA history had a low frequency (less than 50%} of attacks with VA. The auras occurred exclusively prior to the HA in 57%. The free interval between the end of the VA and the start of the HA was usually (75%) shorter than 30 minutes. Most (59%) patients had VAs that lasted from 1 to 30 minutes. They started in the periphery of the visual fields in 56%. The most common phenomena described were: small bright dots (42%), flashes of light (39%), "blind spots" (32%), and "foggy vision" (27%). Fortification spectra was reported by only 20%. Although most (65%) patients had a combination of phenomena, the majority (72%) had only one uniform constellation of manifestations. There was no clear-cut relationship between side of VA and side of HA.
Migraine VA is a pleomorphic and complex symptom. Many patients not qualifying for the diagnostic criteria of migraine with aura, as proposed by the International Headache Society (IHS) unequivocally present with visual phenomena that strongly suggest this diagnosis.