Abstracts

Rationale: The corpus callosum is the largest commissural fiber connecting the left and right cerebral hemispheres, and the electrical activity of both hemispheres is transmitted through the corpus callosum and is regulated. Effects of corpus callosotomy, which is performed to relieve seizures of refractory epilepsy, vary from cases of completely ineffective to cases where long-term seizure remission can be obtained, and it is difficult to predict before surgery. In this study we analyzed the possible determinants for a better seizure outcome after corpus callosotomy. Methods: Of 182 children under the age of eighteen who underwent corpus callosotomy, 157 patients (91 boys) who were followed for more than 1 year were included. Charts were reviewed retrospectively for clinical data and examined for factors related to seizure outcome. In the operation type, there were 134 cases of complete callosotomy, 21 cases of anterior callosotomy and 2 cases of posterior callosotomy. The median age at surgery was 4 years 2 months (3 months to 18 years 0 months), the median follows up period was 3 years and 8 months (12 months to 10 years 8 months). Results: Sixty-four patients (40.8%) experienced at least one seizure free period of more than 1 month or longer, however, 46 out of whom had relapsed in about 2 years. 18 patients (11.5%) who had complete remission of seizures had significantly shorter period from onset to surgery (p = 0.0140), number of antiepileptic drugs before surgery (p = 0.0007) compared to survival or recurrence group. The type of preoperative seizure (p = 0.0009) was also small. Besides, there were more patients had a temporary remission in the preoperative treatment history in the complete seizure remission group (p = 0.0273). In seizure types, seizures disappear in more than 80% in generalized tonic-clonic seizures, generalized tonic seizures, generalized clonic seizures, and absences. But spasms and myoclonus showed a low remission rate of less than 50%. As a result of multivariate analysis, the history of a temporary remission in the preoperative treatment (p = 0.024) and the number of internal medicine before the operation (p = 0.015) were confirmed strong association with complete seizure remission by corpus callosotomy. Conclusions: From the results of this study, it seems that all prognostic factors in the case of complete remission suggest the mildness of the disease. A group of patients whose complete seizure remission can be obtained by corpus callosotomy may be in a state where the seizure is relatively easy to control. Funding: This research received Health and Labor Sciences Research Grants from the Ministry of Health Labor and Welfare of Japan.