Abstracts

Rationale: Patients with low grade neoplasms are experiencing increasing length of survival after resective surgery. Prolonged use of antiepileptic drugs (AEDs) in these patients is associated with morbidity due to medication side effects. Most patients receive prophylactic treatment with AEDs immediately postoperatively. Determining which patients can safely discontinue AEDs remains a clinical challenge. In this study, we examined patients who have undergone surgery for low grade supratentorial brain tumors to determine characteristics of patients who underwent AED withdrawal and subsequently had seizures. Methods: A retrospective chart review was performed in patients who underwent surgical treatment for low grade supratentorial brain tumors between 1/1/05 and 12/31/05 at the Brigham and Women’s Hospital. Data were collected regarding the continued use or withdrawal of postoperative AEDs, occurrence post-AED withdrawal seizure, occurrence of postoperative seizures without AED withdrawal, tumor grade/location/recurrence, degree of resection, and history of preoperative seizures. Patients with less than 1 month of follow-up were excluded from the study. Results: A total of 115 patients were examined with a median follow-up of 3.1 years; these included 73 meningiomas, 10 astrocytomas, 18 oligodendrogliomas, 6 mixed oligoastrocytomas, 2 glioneuronal tumors, and 6 other tumors of indeterminate pathology but with low grade features. AEDs were withdrawn or never started in 65 patients; they were continued in 32 patients; in 18 patients, the status of AED use could not be determined from the chart review. In no patients were AEDs withdrawn if postoperative seizures occurred. Of 65 patients in whom AEDs were withdrawn/not started, post-withdrawal seizures occurred in 8. In 5 of them, there was recurrence/progression of tumor, and in 4 of them, tumor was incompletely resected. In the remaining 57 patients in whom AEDs were withdrawn, 15 had recurrence/progression, and 14 had incomplete resection of tumor. Of 32 patients whose AEDs were not withdrawn, postoperative seizures occurred in 14 of whom 12 had a history of preoperative seizures. Of 42 patients with a history of preoperative seizures, 12 patients had AEDs withdrawn, of whom 2 patients had subsequent seizures. Of 25 patients with temporal lobe tumors, 11 patients had AEDs withdrawn, of whom 1 patient had subsequent seizures. Preoperative seizures and temporal lobe location of tumors were significant predictors of postoperative seizures. However, these were not significant factors in post-AED withdrawal seizures. Conclusions: Our results indicate that approximately 12 percent of patients whose AEDs are withdrawn after surgery for low grade tumors experience post-withdrawal seizures. Most of these patients remained seizure free even if there was tumor recurrence or incomplete resection. The presence of preoperative seizures and temporal location were risk factors for postoperative seizures, but these factors were not significant in our small sample of post-AED withdrawal seizures.