ANTERIOR CALLOSOTOMY FOR INTRACTABLE EPILEPSY - OUTCOME IN A SERIES OF 20 PATIENTS

This series reports 20 patients with intractable epilepsy who underwen t corpus callosotomy during the period 1984-1993. The mean age of pati ents at the time of onset of seizures was 9 years and at the time of c allosotomy 26 years. The seizure types were generalized tonic-clonic ( 18/20), drop attacks (13/20), absences (12/20) and complex partial sei zures (8/20). The most common electroencephalographic (EEG) abnormalit ies were 'bilateral multiple spike and wave' (7/20), or 'generalized/m ultifocal 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 seiz ures and 10 additional patients experienced significant sustained redu ction in the severity and frequency of the seizures. In total, 16 of 2 0 patients (80%) had a favourable outcome. The type of seizures associ ated with the most improved outcome were drop attacks, and generalized tonic-clonic seizures, in 11/13 and 14/18 of the patients, respective ly. No relationship was established between seizure control and preope rative EEG patterns, computed tomography or magnetic resonance imaging findings. The most frequent complication was transient mild left hemi paresis that occured in four patients. The mortality was nil. This stu dy confirms the efficacy of corpus callosum division as a surgical opt ion for selected patients with medically intractable epilepsy. In addi tion, results suggest that the history and clinical classification of the seizures have prognostic value as selection criteria for patients referred for this operation.