EEG changes induced by vigabatrin monotherapy in focal epilepsy.

The effect of vigabatrin (GVG) monotherapy on EEG interictal abnormalities and on background activity recorded at rest and during mental tasks was studied in 14 patients suffering from focal epilepsy. A long-term EEG monitoring was performed in each patient before and 3 months after the beginning of GVG therapy. Ictal and interictal EEG abnormalities (IEA) were quantified by specific computer programs. Background activity was evaluated by spectral analysis at rest with eyes closed (EC), during blocking reaction (BR) and during fixation of cartoons (FIX). During treatment, IEA was either decreased or unmodified independently from seizure occurrence, which clearly improved in the majority of patients. The only EEG modifications induced by GVG monotherapy were a more pronounced slowing of the background activity at rest with EC and a reduced responsiveness to BR. EEG data suggest a GVG monotherapy induced mild "sedative" action on attentive tasks rather than on cognitive function.