Absence seizures aggravated by valproic acid

Purpose: To report on pediatric patients with absence epilepsy who experienced absence seizure aggravation while receiving valproic acid (VPA). Methods: The charts of all children from four pediatric epilepsy clinics receiving VPA for absence epilepsy were reviewed. Patients were evaluated and followed up between 1994 and 2000. Results: Eight cases (six boys) of absence seizure aggravation were detected. Mean age at seizure onset was 5.8 years (range, 3-12 years). Six patients had simple absence seizures, one had myoclonic absences, and one had absences with automatisms. The electroencephalogram in all cases depicted generalized 3-Hz spike-and-wave activities. All eight patients experienced an increase in the frequency of absence seizures within days of VPA introduction. Dose increments resulted in further seizure aggravation. Serum levels of VPA were within therapeutic range in all patients. No case was attributed to VPA-induced encephalopathy. All patients improved on VPA discontinuation. In five children, VPA was reintroduced, resulting in further seizure aggravation. Conclusions: VPA can occasionally provoke absence seizure aggravation in patients with absence epilepsy.