Vigabatrin in drug-resistant partial epilepsy: a 5-year follow-up study.

We treated 75 patients with drug-resistant complex partial seizures and secondarily generalized seizures with vigabatrin as additional therapy for 6 months. Twenty-one patients either showed no benefit from vigabatrin treatment or had side effects. The remaining 54 patients entered into the long-term study. The median monthly seizure frequency decreased from 12.5 at baseline to 3.3 at the 3-month visit, and was 3.9 after 5 years of therapy in 28 patients who continued using the drug after the 5-year period. During 5 years of therapy with vigabatrin, 26 patients have withdrawn from the study because of various reasons: loss of efficacy (14), suspected side effects (5), noncompliance (3), administrative reasons (2), pregnancy (1), and epilepsy surgery (1). In all, 19 patients had a greater than 50% seizure frequency reduction at 5 years, representing 35% of the 54 patients who entered the long-term study, or 25% of the 75 patients who were initially recruited into the efficacy study.