HEMI-FIELD PATTERN-REVERSAL VISUAL-EVOKED POTENTIALS IN MIGRAINE

A study of hemi-field pattern reversal visual evoked potentials record ed in the interictal phase was carried out in 44 patients (22 with mig raine with aura, 22 without aura) in order to determine whether migrai ne patients with or without aura and with headaches with strong unilat eral predominance, either left or right, exhibit abnormalities after h emi-field stimulation. No differences of P100 latency were found betwe en them and a group of 20 normal individuals, between patients sufferi ng from migraine with aura and migraine without aura and between the a ffected and the non-affected side of the head. Only in a subgroup of 1 4 patients with headaches constantly lateralized to a single side, eit her left or right, was the P100 latency significantly shorter on the a ffected side (p < 0.001, t-test) compared with the contralateral non-a ffected side. The results indicate that in both types of migraine ther e is a common underlying pathogenetic mechanism and the affected retro chiasmatic optic radiation has an increased response to sensory input modulation.