Anticonvulsant prophylaxis and timing of seizures after aneurysmal subarachnoid hemorrhage

Objective: There is no evidence that seizure prophylaxis is indicated after aneurysmal subarachnoid hemorrhage (SAH). This study examines prophylactic antiepileptic drug (AED) prescription and the occurrence of seizures within a single university-affiliated institution. Methods: The authors reviewed 95 SAH patient charts using standardized forms. Variables included prophylaxis duration, seizure incidence and timing, CT findings, AED adverse events, and 1-year patient follow-up. Results: Prehospital seizures occurred in 17.9% (17/95) of patients; another 7.4% (7/95) had a questionable prehospital seizure. In-hospital seizures occurred in 4.1% (4/95) of patients, a mean of 14.5 +/- 13.7 days from ictus; three of these four patients were receiving an AED at the time of seizure. Inpatient AED were prescribed to 99% of the cohort for a median of 12 (range 1 to 68) days. Approximately 8% of the cohort had posthospital discharge seizures; this included the patients who had prehospital or in-hospital seizures, 50% of whom were receiving AED therapy at the time of the seizure. Adverse effects occurred in 4.1%; none were serious. The thickness of cisternal clot was associated with having a seizure; no other clinical predictors were identified. Having a seizure at any time did not adversely affect outcome. Conclusions: In this SAH population, the majority of seizures happened before medical presentation. In-hospital seizures were rare and occurred more than 7 days postictus for patients receiving AED prophylaxis. The vast majority of putative clinical predictors did not help predict the occurrence of seizures; only the thickness of the cisternal clot was of value in predicting seizures. Patient selection for and the efficacy and timing of AED prophylaxis after SAH deserve prospective evaluation.