Risk of epilepsy in long-term survivors of surgery for aneurysmal subarachnoid hemorrhage: A population-based study in Iceland

Purpose: Epilepsy is known to result from aneurysmal subarachnoid hemorrhag e (SAH). There are no population-based estimates of the absolute risk or th e duration for which this risk is elevated. We have conducted a population- based study in Iceland of the risk of epilepsy after a ruptured cerebral an eurysm to address these questions. Methods: The index patients are all of the patients who presented with SAH caused by ruptured cerebral aneurysm in Iceland during an Ii-year period (1 958 to 1968) and survived more than 6 months. We determined the number of i ndex patients who developed epilepsy. The observed number of cases of epile psy was compared with that expected based on the incidence of epilepsy in I celand. Results: There were 44 index patients; 11 (25%) developed epilepsy, all wit hin 4 years of the insult. Seven (70%) of 10 patients with acute symptomati c seizures (defined as seizures during the first 2 weeks after the hemorrha ge) developed epilepsy (relative risk, 7.0; 95% confidence interval, 2.3-21 .6). Epilepsy was more frequent in patients with severe neurological residu a (48%) compared with patients without (20%) (relative risk, 2.5; 95% confi dence interval, 0.9-6.3). Conclusions: The risk for epilepsy among survivors of SAH caused by rupture d cerebral aneurysm is substantially increased. Both acute symptomatic seiz ure and persistent neurological impairment are associated with a further in crease in the risk of epilepsy.