Pattern reversal visual evoked potentials in classic and common migraine.

Pattern reversal visual evoked potentials (PVEPs) to transient checkerboard were recorded in 19 patients with migraine with visual aura (i.e., classic migraine), 14 patients with migraine without aura (i.e., common migraine) in the interictal period and 43 normal subjects. Latencies and amplitudes of PVEPs in each group were analyzed. In classic migraine patients, P100 amplitude was significantly higher than in normal subjects (p < 0.01), whereas latencies of PVEPs did not significantly differ. There were no significant differences between the common migraine and normal subjects, nor within the classic and common migraine groups in latencies and amplitudes of PVEP. Four patients with classic migraine underwent PVEPs during or 1-2 h immediately after their migraine attacks. Two of these patients who underwent PVEPs 1.5-2 h after their attacks showed abnormally increased PVEP amplitudes. These results suggest that there are different pathophysiologies in the visual pathway between classic and common migraine and furthermore, classic migraine patients in interictal periods may have hyperexcitability in the visual pathway and that the increased amplitude of PVEPs after attacks may be due to cortical spreading depression.