Abstracts

Rationale: Corpus callosotomy is usually performed to alleviate drop attacks. However, it has been reported that long-term seizure remission is not rare especially in pediatric population and resective surgery can be planned secondary after corpus callosotomy. This study was performed to revise the role of corpus callosotomy in the treatment of pediatric patients with drug-resistant epilepsy. Methods: This study included consecutive 40 patients who underwent corpus callosotomy between January 2011 and April 2016 in our institution. Clinical characteristics and seizure outcome at the last follow-up were retrospectively reviewed. Median age at surgery was 6 years (0 – 18), and mean follow-up period was 30 months (9 – 75). All patients were characterized by generalized seizures and generalized and/or multi-focal EEG abnormalities. Total corpus callosotomy was performed in 34 patients. Pre-operative MRI was normal in 10, unilateral hemispheric lesion in 4, unilateral local lesion in 13 patients. The other patients had diffuse or bilateral lesions. Etiology of epilepsy included unknown in 27, polymicrogyria in 3, subcortical band heterotopia in 3, and tuberous sclerosis in 2 patients. Results: Post-operative seizure outcome at the last follow-up was class 1 in 7 (17.5%), class 4 in 11 (27.5%), class 5 in 19 (47.5%), and undetermined in 3 patients based on ILAE classification. Those with class 1 outcome were limited to 4 cases with normal MRI and 3 cases with unilateral lesion. None of the patients with bilateral MRI lesions achieved class 1 outcome. Subsequent evaluation revealed unilateral epileptogenic focus, and secondary resective epilepsy surgery was planned in 7 patients. Conclusions: Corpus callosotomy can be indicated for pediatric patients with generalized seizures and EEG abnormalities more positively than previously thought. Patients with normal MRI have relatively high chance of long-term seizure remission after corpus callosotomy. Resective epilepsy surgery is planned secondary after corpus callosotomy in a subset of patients, while corpus callosotomy per se infrequently provide long-term seizure remission even in those with unilateral lesion. Funding: Intramural Research Grant (28-4: Clinical Research for Diagnostic and Therapeutic Innovations in Developmental Disorders) for Neurologicaland Psychiatric Disorders of NCNP.Grant-in-Aid for Scientific Research (No. 16K10780) from the Japan Society for the Promotion of Science.