491 Postoperative Seizure Incidence is Not Affected by Extended Duration of Prophylaxis for Metastatic Brain Tumors

INTRODUCTION: There are no formal guidelines for prescribing seizure prophylaxis after cranial tumor resection, despite significant incidence of seizure. Current clinical decision-making regarding its prescription and duration of use could be better informed by data on postoperative seizure incidence and side effect burden. We aim to address this gap in a cohort of patients with metastatic brain tumors. METHODS: We identified seizure-naive patients at our institution who underwent surgical resection of metastatic-origin cranial tumors. A univariate Cox proportional-hazards model assessed associations between postoperative seizure prophylaxis and six-month seizure incidence. We used chi-squared tests to determine relationships between duration of prophylaxis and incidence of seizures or adverse medication effects. Finally, multivariable logistic regression investigated if comorbidities or clinical factors predicted receiving seizure prophylaxis. RESULTS: 159 patients were analyzed (mean age=63.0 ± 11.6 years). 79.9% (N = 129) received postoperative seizure prophylaxis. 11.9% (N = 19) experienced at least one seizure within six months, and 18 were prescribed prophylaxis. Prophylaxis was not associated with decreased seizure incidence (P = 0.997). There was no difference in seizure incidence by treatment duration <1 versus >1 month. Reasons for discontinuation included clinician decision (N = 69, 58.4%), patient preference (N = 30, 25.4%), or mortality (N = 25, 21.1%). 82 patients (64.6%) taking prophylaxis experienced at least one side effect including agitation or somnolence. Side effect incidence trended significantly for treatment duration <1 versus >1 month (P = 0.09). Patients with comorbid dementia were less likely to receive prophylaxis (P < 0.001). CONCLUSIONS: Postoperative seizure prophylaxis and treatment duration were not associated with six-month seizure incidence in patients undergoing surgery for brain metastases. These findings can help inform clinicians to reduce unnecessary anti-seizure prophylaxis prescription. Considering the high prevalence of side effects in our cohort, this may improve postoperative quality of life and reduce costs.