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.