Electrophysiologic effects of gamma-vinyl GABA and carbamazepine

The effects of gamma-vinyl GABA (GVG) and carbamazepine (CBZ) monotherapy on somatosensory (SEP) and visual (VEP) evoked potentials and spectral quantitative EEG (QEEG) were studied in 17 patients with complex partial seizures using a cross-over double-blind study design. CBZ was associated with statistically significant prolongation of SEP latencies. When the drug was switched to GVG, shortening of the peak latencies was observed. Prolonged pattern-VEP peaks were observed both during CBZ and GVG monotherapies. A similar but more subtle tendency of the peaks was observed in P100 latencies. Spectral EEG revealed a slowing of the occipital rhythm with CBZ. No QEEG changes related to GVG were found. The use of multimodal evoked potentials and QEEG should be considered in studying the effects of new antiepileptic drugs (AEDs).