A step-by-step resection guided by electrocorticography for nonmalignant brain tumors associated with long-term intractable epilepsy

To delineate a surgical strategy for long-term intractable epilepsy associated with nonmalignant brain tumor, we developed a protocol for 25 patients whereby removal of tumor alone and additional irritative peritumoral tissue between sulci (gyrectomy), as well as further resectioning, was performed based on intraoperative electrocorticogram results. In five patients, no irritative zones were observed that required resectioning following complete removal of tumors. Additional gyrectomy was indicated in 18 patients who demonstrated gliosis or cortical dysplasia in the peritumoral residual irritative zone. Remote irritative zone observed in two patients was correlated with long-term and frequent seizures. During a follow-up period of at least 5 years, seizure outcome was Engel category I in 92%, and all patients have remained tumor-free. Peritumoral gyrectomy as a means of removing likely epileptic tissue following tumor resection appears to be a useful method for treating long-term intractable tumoral epilepsy. Further resectioning of remote tissue should be considered in patients with severely intractable seizures.