The risk of seizure following surgery for brain arteriovenous malformation: a prospective cohort study

Background: The evidence for the risk of seizures following surgery for brain arteriovenous malformations (bAVM) is limited. Objective: To determine the risk of seizures after discharge from surgery for supratentorial bAVM. Methods: A prospectively collected cohort database of 559 supratentorial bAVM patients (excluding patients where surgery was not performed with the primary intention of treating the bAVM) was analyzed. Cox proportional hazards regression models (Cox regression) were generated assessing risk factors, a Receiver Operator Characteristic curve was generated to identify a cut-point for size and Kaplan–Meier life table curves created to identify the cumulative freedom from postoperative seizure. Results: Preoperative histories of more than 2 seizures and increasing maximum diameter (size, cm) of bAVM were found to be significantly (P < .01) associated with the development of postoperative seizures and remained significant in the Cox regression (size as continuous variable: P = .01; hazard ratio: 1.2; 95% confidence interval: 1.0-1.3; more than 2 seizures: P = .02; hazard ratio: 2.1; 95% confidence interval: 1.1-3.8). The cumulative risk of first seizure after discharge from hospital following resection surgery for all patients with bAVM was 5.8% and 18% at 12 mo and 7 yr, respectively. The 7-yr risk of developing postoperative seizures ranged from 11% for patients with bAVM ≤4 cm and with 0 to 2 preoperative seizures, to 59% for patients with bAVM >4 cm and with >2 preoperative. Conclusion: The risk of seizures after discharge from hospital following surgery for bAVM increases with the maximum diameter of the bAVM and a patient history of more than 2 preoperative seizures.