Electroencephalographic generalized features in idiopathic childhood focal epilepsies

PURPOSE Idiopathic focal epilepsies in childhood including benign childhood epilepsy with occipital paroxysms (BEOP) or benign childhood epilepsy with centro-temporal spikes (BCECTS) are characterized by specific focal electrographic patterns as the name indicates. Generalized spike-wave discharges in children with idiopathic focal epilepsy can suggest a neurobiological continuum with the idiopathic generalized epilepsies. We assessed the prevalence of generalized epileptiform discharges and generalized seizures in BEOP/BCECTS patients. METHODS Between August 2005 and November 2008, we identified 220 cases with electroclinical features typical of idiopathic focal epilepsies, 172 patients with BCECTS and 48 patients with BEOP, excluding patients whose neurological examinations or brain MRI were abnormal. We analyzed gender, age at onset, manifestation of generalized seizures, and serial EEG records to detect generalized abnormalities. RESULTS Of our population, 42 patients (19.1%, 22 boys), 30 (17.4%) of 172 BCECTS patients and 12 (25.0%) of 48 BEOP patients, showed generalized spike-wave discharges once or more during follow-up. The typical 3-Hz generalized spike wave discharge was noticed in 7 patients and concurrence with clinical generalized seizure was observed in 11. CONCLUSION A relatively high incidence of generalized spike-wave discharge and concurrence with generalized seizure were observed in patients with BEOP/BCECTS, with the incidence being higher in BEOP patients than in those with BCECTS. It may be inferred that idiopathic focal epilepsy is not a fixed syndrome but is a part of a broad, age-related, benign, seizure susceptibility syndrome.