Callosotomy in the treatment of drug-resistant epilepsy
At the present time corpus callosotomy is a valuable option in the management of some patients with drug-resistant epilepsy who are not candidates for resective procedures. The records of six patients who underwent callosotomy at 'Hospital Virgen de las Nieves' (Granada, Spain) in the past four years were retrospectively analyzed. The patients all had intractable primary or secondarily generalized seizures, were severely handicapped by its frequency and nature (especially with drop attacks and multiple injuries) and were not suitable for other surgical procedure. The results of surgery (five anterior callosotomies and one subtotal section) are described after an average follow-up period of 2.5 years. Overall, four patients achieved significant improvement (at least 50% reduction in seizure frequency, severity, or both, affecting quality of life), with a marked reduction (> 75%) in two of them. There was no clinical deterioration, significant surgical complication nor relevant additional long-term neuro-psychological deficit in any case. Previous studies have been reviewed mainly to find those prognostic factors associated with a better seizure outcome or with the occurrence of complications. The best results are obtained in those patients with drop attacks (including atonic seizures) as the most frequent and disabling seizure type. According to the type of epilepsy, patients with localization-related epilepsy (especially when symptomatic of a focal brain damage) and those with the Lennox-Gastaut syndrome are the most likely to benefit from the procedure. It is suggested that, in the first place, a two-thirds anterior callosotomy should be performed particularly with atonic seizure are the most frequent seizure type. We may proceed with completion of callosal division as a second stage in those patients in whom a significant improvement has not been observed. In severely retarded patients with multiple seizure types, one-stage complete section may be performed. The procedure is relatively safe, with a low incidence of morbidity and clinically significant long-term neuro-psychological deficits. Further larger clinical studies are necessary to elucidate many aspects which are still unresolved. More uniformity would be desirable in the evaluation of patients, surgical technique, follow-up and presentation of results.