Antiepileptic drug withdrawal in patients with temporal lobe epilepsy undergoing presurgical video-EEG monitoring

Purpose: To investigate antiepileptic drug (AED) withdrawal during video-EEG monitoring in adult patients with temporal lobe epilepsy (TLE). Methods: Between 1995 and 1997, 102 consecutive patients with refractory TLE were admitted to the epilepsy monitoring unit for presurgical evaluation. Patients were monitored with ongoing AEDs being rapidly decreased and discontinued in 4-6 days. The monitoring was continued until sufficient numbers of seizures were recorded. Serum AED levels were checked at admission and after the first complex partial seizure (CPS). Results: In all, 89 patients had 429 CPSs (mean, 4.8 per patient), including 156 (36.4%) secondarily generalized. A mean of 153.8 h (16-451 h) was required for completing the monitoring in each patient. Forty-three (48.3%) patients experienced seizure clusters, and eight (9.0%) had generalized seizures that had never occurred or had been absent for years. However, none evolved to status epilepticus. Carbamazepine was the most commonly used AED in 71.9% of patients, followed by valproate and phenytoin. When the first CPS occurred, mean 77.2 h since the beginning of the monitoring, serum levels of these three AEDs were mostly subtherapeutic rather than minimal. Conclusions: Acute AED withdrawal effectively provoked seizures in TLE patients undergoing presurgical video-EEG monitoring. However. nearly 50% of patients had seizure clusters or secondarily generalized seizures. Serum AED levels were mostly subtherapeutic when the first CPS occurred.