Pattern reversal visual evoked potentials in migraine with aura and migraine aura without headache

Pattern reversal visual evoked potentials (PVEPs) were recorded in 20 patients with migraine with aura (MA), 19 patients with migraine without headache (migraine equivalent; ME.) during interictal periods, and 34 normal subjects. All migraine patients had hemianopsia or fortification spectra during attacks. In both MA and ME patients of less than 49 years of age, there were significant ( p <0.01) differences in amplitude of PVEPs at the mid-occipital and contralateral to visual aura electrode sites compared to normal subjects. Amplitude of PVEPs in MA and ME showed significant ( p <0.001) increases when recorded soon after attacks, especially within 10 days. There was a significant ( p <0.0l) correlation between percentage asymmetries and the duration of illness in both MA and ME. We conclude from our PVEP findings that cortical spreading depression remains the most likely explanation for the migraine visual aura.     

Pattern reversal visual evoked potentials in children with migraine or tension-type headache

Pattern reversal visual evoked potentials were recorded in 71 children with different types of migraine (e.g. migraine with aura, migraine without aura) or tension-type headache and in 19 controls (mean age of both groups 9 years). P100 latencies were comparable in all three groups.     

Hemi-field pattern reversal visual evoked potentials in migraine

A study of hemi-field pattern reversal visual evoked potentials recorded in the interictal phase was carried out in 44 patients (22 with migraine with aura, 22 without aura) in order to determine whether migraine patients with or without aura and with headaches with strong unilateral predominance, either left or right, exhibit abnormalities after hemi-field stimulation. No differences of P100 latency were found between them and a group of 20 normal individuals, between patients suffering from migraine with aura and migraine without aura and between the affected and the non-affected side of the head. Only in a subgroup of 14 patients with headaches constantly lateralized to a single side, either left or right, was the P100 latency significantly shorter on the affected side (p < 0.001, t-test) compared with the contralateral non-affected side. The results indicate that in both types of migraine there is a common underlying pathogenetic mechanism and the affected retrochiasmatic optic radiation has an increased response to sensory input modulation.     

Influence of disease duration on visual evoked potentials in migraineurs

OBJECTIVE: To determine the possible influence of the duration of migraine on pattern-reversal visual evoked potentials. METHODS: An investigation was conducted in 49 patients with migraine without aura according to the International Headache Society criteria. Twenty-two of these patients had had migraine for 2 years or less (group 1), and the other 27 patients had had the disease for 10 years or more (group 2). The control group consisted of 17 healthy subjects. RESULTS: Comparison of the mean P100 latency and amplitude showed no significant difference among the groups. There was, however, a good negative correlation between age and latency (r = -0.59, P =.003) in group 1, but no such correlation was observed for group 2 or the control group. CONCLUSIONS: It was concluded that the duration of migraine has no influence on pattern-reversal visual evoked potentials and that the pathogenesis of early- and late-onset migraine may be different.     

Influence of colors on habituation of visual evoked potentials in patients with migraine with aura and in healthy volunteers

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.     

Nociceptive blink reflex and visual evoked potential habituations are correlated in migraine

BACKGROUND: Lack of habituation, as reported in migraine patients between attacks for evoked cortical responses, was also recently found for the nociceptive blink reflex (nBR) mediated by brainstem neurons. It is not known if both brain stem and cortical habituation deficits are correlated in the same patient, which would favor a common underlying mechanism. OBJECTIVE: To search for intraindividual correlations between habituation of pattern reversal-visual evoked potentials and that of the nociception-specific blink reflex in migraineurs and in healthy volunteers (HV). METHODS: We recorded 15 HV and 15 migraine without aura patients between attacks. Habituation for visual evoked potentials was measured by comparing the N1-P1 amplitude change (%) between the first and sixth block of 100 sequential averaged responses. Habituation for the nBR was defined as the percentage change of the R2 response area between the 1st and 10th block of five averaged EMG responses, elicited by stimulating the right side every 2 minutes for 32 minutes. We also calculated the slope of N1-P1 amplitude and R2 response area changes from the first to the last response and the correlation with attack frequency. RESULTS: A significant habituation deficit in both cortical and brain stem evoked activity characterized on average the group of migraineurs compared to controls. In migraine patients, but not in HV, we found a significant positive correlation between habituation of pattern reversal-visual evoked potentials and that of the nociception-specific blink reflex both for the degree of habituation between first and last blocks of averagings (r = 0.703; P = .003) and for the habituation slope (r = 0.751; P = .001). Moreover, nBR habituation was positively correlated with attack frequency (r = 0.548; P = .034). CONCLUSION: The positive correlation between visual evoked potential and nBR habituations is consistent with the idea that in migraine the same neurobiological dysfunction might be responsible for the habituation deficit both in cortex and brain stem. As nBR habituation increases with attack frequency, its interictal deficit is unlikely to be due to trigeminal sensitization.     

Topographic analysis of steady-state visual evoked potentials (SVEPs) in the medium frequency range in migraine with and without aura

Topographic analysis of SVEPs in the medium frequencies range was performed in 30 migraineurs without aura, 20 migraineurs with aura and in 20 control subjects. The mean absolute power values of the fundamental component F1, the subharmonic F1/2 and the first harmonic F2, corrected by logarithmic transformation, were computed in each group and then compared using Student's t-test. The interhemispheric coherence of the F1 component was also evaluated. The 18, 21, and 27 Hz F1 components were increased in both migraineurs with and without aura, particularly in the temporo-parietal regions. The 24 Hz F1 component was augmented only in migraineurs without aura in the parieto-occipital regions in comparison with migraineurs with aura and controls. Migraine with aura patients had a reduced interhemispheric coherence mostly of 12 Hz and 15 Hz F1 components in frontal and temporo-parietal regions. Results of the study confirm abnormalities of SVEPs in migraineurs with and without aura. These consist of widespread increases of F1 components in the medium frequency range over the temporo-parietal regions.     

Habituation of visual and intensity dependence of auditory evoked cortical potentials tends to normalize just before and during the migraine attack

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.     

图形翻转视觉诱发电位在视觉通路肿瘤中的应用

目的 探讨图形翻转视觉诱发电位（pattern reversal visual evoked potentials,PRVEP)在视觉通路脑肿瘤诊断中的应用价值。方法 对83例经CT和/或MRI证实为视觉通路脑肿瘤的患者和20例正常人进行PRVEP检查。其中24例患者48只眼同时行眼科全自动视野计检查。结果 患病组和对照组之间PRVEPP100波潜伏期和波幅明显不同，视觉通路上不同部位的脑肿瘤有不同的PRVEP特征表现，PRVEP的变化类型与视野之间密切相关。结论 PRVEP监测能灵敏反映病变对视觉通路的损害，并有助于视路脑肿瘤的早期诊断，定位及视觉功能状态的评价。具有重要的临床应用价值。     

Transient visual disturbances during migraine without aura attacks

OBJECTIVE: To evaluate the prevalence and clinical features of transient visual disturbances (TVDs) during migraine without aura (MO) attacks and to point out any similarities with the disturbances listed among the diagnostic criteria of the International Headache Society (IHS) classification for migraine with aura (MA). METHODS: We studied a sample of 191 patients (145 women and 46 men) with MO and no other associated forms of primary headache who had been referred to the University of Parma Headache Centre between December 1, 1999 and December 1, 2000. RESULTS: A total of 165 patients reported that they had never experienced TVDs during their MO attacks. In the remaining 26 patients (19 women and 7 men), MO attacks were at times accompanied by TVDs, which were present in over 30% of MO attacks in 65.4% of patients. In about 60% of cases, TVDs lasted less than half a minute. TVDs consisted of phosphenes in most patients, general blurring of vision in about one-fourth, and scintillating scotomas in 15%. In 73% of cases, TVDs occurred during the headache phase, whereas in the remainder they preceded it. Strict application of the IHS diagnostic criteria would have led to a diagnosis of MA in 12 cases, corresponding to 46% of our MO patients with TVDs and to 6.3% of all patients with an established clinical diagnosis of MO. CONCLUSION: The results of our study suggest that current IHS diagnostic criteria for MA may lead to an overestimation of MA cases.     

Recurrent Lilliputian hallucinations as visual aura symptom in migraine

Since her early 30s a 72-year-old female migraine sufferer has experienced recurrent episodes of Lilliputian hallucinations occurring at the peak of her severe migraine attacks and lasting between 2 min and 5 min, suggesting that her miniature hallucinations represent a visual migraine aura symptom. The existence of Lilliputian hallucinations of a migrainous nature is confirmed by four similar case reports reviewed from the migraine literature. The occurrence of similar Lilliputian hallucinations in the syndrome of peduncular hallucinosis, due to mesencephalic and/or thalamic lesions, supports the notion that the patient's recurrent Lilliputian hallucinations might have been aura symptoms of basilar migraine.     

Responsiveness of the visual system in childhood migraine studied by means of VEPs

We have tried to ascertain whether the increased visual evoked potential (VEP) amplitude found in adult migraineurs is present also in children with migraine. We investigated 43 children, 26 male and 17 female, with a mean age of 11.4 years, 24 with common and 19 with classic migraine, and compared them with a control group of 20 children, 11 male and 9 female, with a mean age of 9.7 years. Flash and pattern reversal VEPs were recorded in both groups, and the study was carried out in the pain-free interval between attacks. The children with migraine showed a significant (p less than 0.01) increase in VEP amplitude on flash stimulation but not on pattern reversal. There were no differences between classic and common migraine. The abnormal responsiveness of the visual system seems to be related to variations in light intensity rather than to spatial contrasts.     

短潜伏期体感诱发电位和闪光视觉诱发电位对脑出血患者预后的判断

目的近年来有多种诱发电位(EP)和脑外伤预后显著相关的报道,而EP和脑出血预后的关系还未见报道。本实验旨在了解发病早期短潜伏期体感诱发电位(SLSEP)、闪光视觉诱发电位(F-VEP)和脑出血近期预后的关系。方法81例脑出血患者均在发病48h内行SLSEP、F-VEP检查、Glascow昏迷评分(GCS),出院或死亡时进行Glascow预后分级(GOS)。结果SLSEP的中枢传导时间(CCT)、N20、F-VEP的N2和脑出血患者的GCS、GOS均显著相关。结论SLSEP和F-VEP是评价脑出血近期预后的有效手段。     

EEG spectral analysis in migraine without aura attacks

In 16 patients suffering from migraine without aura, we examined quantitative EEG and steady-state visual evoked potentials (SSVEPs) at 27 Hz stimulation during the critical phase of migraine and in attack-free periods. The main spontaneous EEG abnormalities found during the critical phase were the slowing and asymmetry of the dominant frequency in the alpha range. The amplitude of the SSVEP F1 component was significantly reduced during the attack phase compared with the intercritical phase; in the latter condition the visual reactivity to 27 Hz stimulus was increased over almost the entire scalp compared with normal subjects. The EEG abnormalities confirm a fluctuating modification of alpha activity during the migraine attack, probably related to a functional disorder. The suppression of visual reactivity during the migraine attack could be related to a phenomenon of neuronal depolarization such as spreading depression, occurring in a situation of central neuronal increased excitability predisposing to migraine attacks.     

Auditory event-related potentials and reaction times in migraine children

Cognitive processing was investigated interictally in 18 children with migraine without aura and 18 age-matched controls by measuring event-related potentials (ERPs) and reaction times (RTs) during an acoustic oddball paradigm. Results showed that N100 amplitude evoked by frequent stimuli was significantly smaller in patients compared with controls. Habituation of target P300 amplitude was observed in patients but not in controls. Mean RTs were equivalent in the two groups, but migraine children made more errors than controls.     

Search for correlations between genotypes and electrophysiological patterns in migraine: the MTHFR C677T polymorphism and visual evoked potentials

Interictally, migraineurs have on average a reduction in habituation of pattern-reversal visual evoked potentials (PR-VEP) and in mitochondrial energy reserve. 5,10-Methylenetetrahydrofolate reductase (MTHFR) is involved in folate metabolism and its C677T polymorphism may be more prevalent in migraine. The aim of this study was to search in migraineurs for a correlation between the MTHFR C677T polymorphism and the PR-VEP profile. PR-VEP were recorded in 52 genotyped migraine patients: 40 female, 24 without (MoA), 28 with aura (MA). Among them 21 had a normal genotype (CC), 18 were heterozygous (CT) and 13 homozygous (TT) for the MTHFR C677T polymorphism. Mean PR-VEP N1-P1 amplitude was significantly lower in CT compared with CC, and tended to be lower in TT with increasing age. The habituation deficit was significantly greater in CC compared with TT subjects. The correlation between the cortical preactivation level, as reflected by the VEP amplitude in the first block of averages, and habituation was stronger in CC than in CT or TT. The MTHFR C677T polymorphism could thus have an ambiguous role in migraine. On one hand, the better VEP habituation which is associated with its homozygosity, and possibly mediated by homocysteine derivatives increasing serotoninergic transmission, may protect the brain against overstimulation. On the other hand, MTHFR C677T homozygosity is linked to a reduction of grand average VEP amplitude with illness duration, which has been attributed to brain damage.