Abstracts

Rationale: Corpus callosotomy was introduced in the early 1940s to treat non-resectable seizures refractory to antiepileptic drugs (AEDs). This procedure reduces the frequency and severity of disabling seizures in conditions including drop attacks, primary and secondary generalized seizures, and mixed seizures such as seen in Lennox-Gastaut Syndrome. However, patients seldom become seizure free, and this procedure may be associated with significant perioperative morbidity and mortality. In seeking to reduce the incidence of adverse events, partial calllosotomies or staged sections have been attempted. As such, the optimal extent of callosal section for different seizure types remains uncertain. This study reviews, in a systematic fashion, the data on traditional microsurgical corpus callosotomy with respect to seizure control as well as the rates of complications, and compares these across extent of callosal section.Methods: We conducted a comprehensive literature search using multiple databases, supplemented with a manual search of bibliographies of reviews, original articles, book chapters, and expert consultation. All full-length articles published in English describing at least 10 patients, with outcomes reported after a mean/median follow-up of >1 year, were includedResults: The search yielded 437 citations of which 86 were selected for full text search and a total of 37 articles were included in the final data set. Across all surgeries, a worthwhile decrease (>50% seizure reduction) was observed in ~77% of patients, while a significant decrease (>75% reduction) was seen in ~54%. The best response was found for seizures described as drop attacks, followed by atonic , generalized tonic-clonic, and absence seizures. Less favorable results were observed for myoclonic, tonic, and complex partial seizures. Generally, seizure reduction improved with greater extent of callosal section ie partial to complete callosotomy (drop attacks: >50% reduction - 66% vs. 85%, p<0.0001; >75% reduction - 54% vs. 77%, p<0.0001). However, more extensive sections were associated with an increased risk of permanent disconnection syndrome (3.9% vs. 0.7%, p<0.0001). Conclusions: Corpus callosotomy is an effective intervention to reduce seizure frequency in selected patients. Greater extent of callosal section is associated with better seizure control, but at the cost of increased risk of surgical complications