Phenobarbital-induced atypical absence seizure in benign childhood epilepsy with centrotemporal spikes.

This report describes atypical absence seizures induced by phenobarbital (PB) in a patient with benign childhood epilepsy with centrotemporal spikes. An 11-year-old girl had nocturnal motor seizures, beginning at the age of 7 years. Interictal EEG displayed centrotemporal sharp waves in the left and right sides alternatively, which increased significantly in frequency during sleep. She was given a diagnosis of benign childhood epilepsy with centrotemporal spike and was treated with valproic acid (VPA), which controlled her seizures for 3 years. She experienced nocturnal Rolandic seizures again, at the age of 10 years 2 months, 10 years 10 months in spite of the regular medication, and PB 60 mg daily was added to the VPA. Her parents noted de novo a few seconds of unresponsive fits 7 days after PB administration. Ictal EEG of the fits revealed diffuse irregular spike and wave bursts (1-4 seconds). VPA and PB in her blood was within the therapeutic ranges. After discontinuing PB, the atypical absence seizures immediately disappeared. Phenobarbital should be added to the list of drugs that potentially provoke de novo seizures.