Anterior callosotomy for intractable epilepsy: outcome in a series of twenty patients

This series reports 20 patients with intractable epilepsy who underwent corpus callosotomy during the period 1984-1993. The mean age of patients at the time of onset of seizures was 9 years and at the time of callosotomy 26 years. The seizure types were generalized tonic-clonic (18/20), drop attacks (13/20), absences (12/20) and complex partial seizures (8/20). The most common electroencephalographic (EEG) abnormalities were 'bilateral multiple spike and wave' (7/20), or 'generalized/multifocal spike and slow wave' (7/20). The follow-up was 5.6 (SD 0.6) years. Six patients have remained free of major generalized motor seizures and 10 additional patients experienced significant sustained reduction in the severity and frequency of the seizures. In total, 16 of 20 patients (80%) had a favourable outcome. The type of seizures associated with the most improved outcome were drop attacks, and generalized tonic-clonic seizures, in 11/13 and 14/18 of the patients, respectively. No relationship was established between seizure control and preoperative EEG patterns, computed tomography or magnetic resonance imaging findings. The most frequent complication was transient mild left hemiparesis that occurred in four patients. The mortality was nil. This study confirms the efficacy of corpus callosum division as a surgical option for selected patients with medically intractable epilepsy. In addition, results suggest that the history and clinical classification of the seizures have prognostic value as selection criteria for patients referred for this operation.