Anticonvulsant prophylaxis and timing of seizures after aneurysmal subarachnoid hemorrhage

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.

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.

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.

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.