Postoperative epilepsy in patients undergoing craniotomy for glioblastoma multiforme

Glioblastoma multiforme (GBM) has associated with it one of the poorest prognoses among brain tumors. Postoperative seizures and the side effects of anticonvulsants, routinely given for prophylactic purposes, add to patient morbidity. The primary goal of this study was to determine who, of those undergoing craniotomy for GBM resection, is at risk for epilepsy. We studied 72 consecutive patients who underwent craniotomy and palliative resection for GBM. Twenty-nine presented with seizures and 17 had postoperative seizures. All patients were treated with a postoperative anticonvulsant for at least six months; anticonvulsants were continued longer if there was a postoperative seizure. Patient factors examined for an association with risk for postoperative seizure included age, sex, tumor size, tumor location, adjuvant therapy, postoperative complications and history of preoperative seizures. The majority of patients with no prior seizure history and who seized postoperatively had their first seizure after withdrawal from their anticonvulsant medication. All, but one, of the patients with both pre- and postoperative seizures had their first postoperative seizure while still on anticonvulsants. Smaller tumor size and frontal resection were associated with an increased risk of postoperative seizures. Our data suggests that those who do not present with seizures and undergo GBM resection may still be prone to seize but more easily protected from postoperative seizures with anticonvulsant therapy than patients who present with seizures; resection of frontal tumors and smaller tumors seemed to indicate an increased risk for postoperative seizures.