Callosotomy for intractable epilepsy: overall outcome.

The effectiveness of callosotomy to the control of medically intractable epilepsy is still discussed fifty years after the first reported cases. Nevertheless patient selection, type of seizures and epileptic syndromes are now better determined. Atonic and tonic astatic seizures characterized both by clinical and electroencephalographical specific patterns, are the most responsive. A favorable outcome, from > 50% reduction in seizure frequency to a complete cessation, is obtained from 60 to 80% of the patients. For tonic-clonic seizures, favorable outcome fluctuates from 40% to 80% principally according to the extension of the section. Other types of seizures are not indicated for callosotomy even though some improvement may be observed. Symptomatic secondary generalized epilepsy with predominent unilateral lesion and epileptic focus on bifrontal lobe epilepsy are the most suitable indication. True generalized epilepsies are associated with a less favorable outcome. Indeed, axial spasms, the most frequent type of drop attacks in the Lennox-Gastaut syndrome, probably do not have a cortical origin. Quality of life and social adjustment are assessed from a cohort of 20 cases of anterior two-third callosotomy. Actual benefits are in close connection with both seizure relief and age at operation. To obtain a gain in social independence not only seizure control has to be better but also surgery must be performed sooner.