Rationale for giving antiepileptics intraoperatively in patients undergoing surgery for supratentorial brain tumors

Background: Early postoperative seizures remain a frequent complication in supratentorial tumor surgery. There is no standard recommendation for additional intraoperative phenytoin administration. Methods: One hundred patients with supratentorial brain tumors undergoing surgery were included. All patients received regular phenytoin preoperatively and received an additional dose of phenytoin intraoperatively. Phenytoin levels were measured in preoperative, intraoperative, and postoperative periods. Presence or absence of seizures in the postoperative period was recorded. Results: The mean preoperative phenytoin values were 15.9 ± 2.623, intraoperative phenytoin levels were 11.38 ± 3.667, and the mean postoperative phenytoin levels were 14.03 ± 2.607. Eight patients developed seizures in the postoperative period. The mean difference between intraoperative and postoperative drug levels was significant in the seizure group as compared to the other group. Conclusion: Intraoperative phenytoin levels dropped in all patients during surgery, but the drop was significantly higher in patients who developed seizures in the postoperative period. The routine measurement of perioperative plasma phenytoin levels may be associated with the use of adding phenytoin intraoperatively to reduce the incidence of postoperative seizures. The aim of our study was to determine the plasma phenytoin levels in intraoperative period which can determine early postoperative seizure risk.