Effect of diazepam on visual potentials evoked by reversible checkerboard pattern

Visual potentials evoked by means of reversible checkerboard pattern were studied in 12 healthy subjects, 5 patients with probable multiple sclerosis and 3 patients with photosensitive epilepsy before and after intravenous injection of 10 mg of Valium. The most characteristic feature was lowering of the amplitude of the evoked visual potentials (in 75%) which appeared as a rule between 30 seconds and 4 minutes after Valium injection. Prolongation of Pmax latency was observed less frequently (in 65%) and this change was of low grade. In nearly half the cases sings of synchronization appeared with development of late multiphasic components of the visual evoked potential. No significant difference was noted in the effect of Valium on the latency and amplitude of the visual evoked potentials between healthy subjects and patients. The possible mechanisms of diazepam action on the conduction in visual pathways are discussed.