Seizures are a potentially devastating complication of surgical resection of brain tumors. Consequently, many neurosurgeons administer prophylactic anti-epileptic drugs (AEDs) in the peri-operative period. However, it is currently unclear whether prophylactic, peri-operative AEDs should be routinely administered to patients with brain tumors who have never had a seizure.

     Consequently, we conducted a prospective, randomized trial examining the use of phenytoin for post-operative seizure prophylaxis in patients with supratentorial brain metastases or gliomas undergoing surgical resection.

       123 patients (77 metastases, 46 gliomas) were randomized, with 62 receiving 7-day phenytoin and 61 receiving no-prophylaxis.

     Eligible patients were randomized to receive either phenytoin for 7 days following tumor resection, or no seizure prophylaxis. Phenytoin levels were monitored daily. Primary outcomes were seizures and adverse events (AEs).

     No significant differences were observed between the Phenytoin Group and the No-Prophylaxis Group in the incidence of all seizures 24% (phenytoin group) vs. 18% (No prophylaxis group), p = 0.40, early seizures (11% vs. 8%, p = 0.56), clinically significant early seizures (2% vs. 3%, p = 0.55), or seizure-free survival (log rank test p=0.58). The Phenytoin Group experienced more AEs (21% vs. 2%, p = <0.01). Therapeutic levels were maintained in 90% of patients.

     This was a prospective randomized trial.

     Prophylactic administration of phenytoin in patients undergoing surgery for metastases or gliomas without prior seizures does not reduce the likelihood of post-operative seizures, and is associated with an increased incidence of AEs.

     The routine use of peri-operative prophylactic phenytoin in this patient population may not be warranted.