Surgical management of pediatric tumor-associated epilepsy

Brain tumors are a common cause of seizures in children. Early surgical tre atment can improve seizure outcome, but controversy exists regarding the mo st appropriate type of surgical intervention. Some studies suggest tumor re section alone is sufficient, while others recommend mapping and resection o f the surrounding epileptogenic foci to optimize seizure outcome. To addres s this issue, we reviewed the charts of 34 pediatric patients aged 18 month s to 20 years with medically intractable epilepsy and primary brain tumors. The average age at operation was 12.6 years, and patients had seizures for an average of 6.4 years. The majority of tumors were located in the tempor al lobe. Seventeen patients, because of tumor location near an eloquent are a, underwent extraoperative mapping using subdural electrode grids prior to definitive tumor resection. Fourteen of these patients had a gross total t umor resection, yet only two had a distinct zone of ictal onset identified and resected. The remaining 17 patients had tumors either in the nondominan t hemisphere or far removed from speech-sensitive areas, and therefore did not undergo extraoperative subdural electroencephalograph mapping. Fourteen of these patients also had a gross total tumor resection, while none had i ntraoperative electrocorticography to guide the resection of additional non tumoral tissue. Overall, of the 28 patients treated with a gross total tumo r resection, 24 (86%) are seizure free, while the other four are significan tly improved. Of the six patients who had a subtotal tumor removal, five ha ve persistent seizures. The mean follow-up was 3.6 years. We conclude that in children and adolescents, completeness of tumor resection is the most im portant factor in determining seizure outcome. The routine mapping and rese ction of epileptogenic foci might not be necessary in the majority of patie nts. As a corollary, the use of subdural electrode grids in pediatric patie nts with tumor-associated epilepsy should be Limited to cases requiring ext raoperative cortical stimulation for localization of nearby eloquent cortex .