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. The studies reported here formed part of a PhD project 4 in which visual function was studied in 92 subjects with migraine and 62 controls, by neurophysiological and psychophysical methods. Here we report the results of investigation by electroretinogram (ERG), SFVEP, and PRVEP. Some preliminary data have already been published.
Methods
SUBJECTSThe patients in this study were not a random sample of the migraine population. They came from a wide age range, and there was a deliberate selection for those with a visual aura and with attacks precipitated by visual stimuli, to provide subgroups large enough for meaningful comparisons. Controls were found among colleagues, the spouses, or friends of subjects with migraine, and other volunteers. All subjects had a visual acuity of 6/6 or better, and none of them had any visual disorder.All 92 subjects fulfilled the International Headache Society (IHS) criteria for a diagnosis of migraine with or without aura.7 There were 72 women and 20 men, aged 16-59 years (mean 40.2 (SD 12.5) years). All were free of headache at the time of testing, and none were taking prophylactic treatment. Forty seven had migraine with aura (MA), 37 had migraine without aura (MO), and eight had both. Results from these eight patients have been included only when the whole migraine group is considered. All patients with MA had a visual aura, and seven also had other aura symptoms. Seventy three patients reported attacks triggered by visual stimuli, such as bright lights, flashing lights, or patterns. Migraine ...