Corpus callosotomy for intractable epilepsy: seizure outcome and prognostic factors.

We reviewed the outcome of corpus callosal section in 64 adult and pediatric patients to identify factors associated with a good outcome: 48% of patients had a favorable outcome for overall seizure frequency. Improvement was noted in several seizure types and was most likely for drop attacks, particularly in the setting of a unilateral focal cerebral lesion or a true generalized epilepsy of Lennox-Gastaut type. Poor outcomes for drop attacks were more likely if there was associated severe intellectual handicap or bilateral independent spikes on interictal EEG. Complex partial seizures (CPS), most commonly of frontal lobe origin, also responded favorably. The complications of callosal section were usually mild and transient. New focal seizures occurred in only 2 patients and were not as frequent or disabling as preoperative seizures types. A worthwhile improvement in seizure outcome was achieved by completion of the callosotomy in 6 of 10 patients with unsatisfactory results from anterior callosotomy.