Incidence and Risk Factors for Intraoperative Seizures During Elective Craniotomy

Background: Perioperative seizures may affect 1% to 50% of patients undergoing craniotomy and adversely impact outcomes. However, data on intraoperative seizures are limited. This retrospective case-control study investigated the incidence and risk factors for intraoperative seizures during elective supratentorial craniotomy involving evoked potential monitoring. Materials and Methods: Patients aged 18 years or above undergoing elective supratentorial craniotomy with evoked potential monitoring who experienced intraoperative seizures at our institution between December 2008 and March 2014 were compared with a control group generated using a random number generator. Six controls were used for each case from among the patients who underwent elective supratentorial craniotomy during the same calendar year. Multivariate analysis was conducted using logistic regression to identify the risk factors for intraoperative seizures. Results: Among the 1916 patients who met the inclusion criteria, 45 (2.3%) had intraoperative seizures. The majority of seizures occurred during burr-hole placement or craniotomy, before lesion manipulation. Timing of seizures relative to motor evoked potential runs and stimulus intensity was variable. Significant risk factors for intraoperative seizures were seizure history (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.07-4.46; P =0.03), diagnosis of brain tumor (OR, 2.41; 95% CI, 1.16-4.19; P =0.02), and temporal craniotomy (OR, 5.18; 95% CI, 2.03-13.25; P =0.001). Intraoperative prophylactic use of phenytoin/fosphenytoin and levetiracetam was protective against seizure (phenytoin/fosphenytoin: OR, 0.12; 95% CI, 0.04-0.35; P <0.001 and levetiracetam: OR, 0.40; 95% CI, 0.17-0.94; P =0.04). Phenytoin/fosphenytoin was more protective than levetiracetam (OR, 0.31; 95% CI, 0.10-0.99; P =0.048). Conclusions: The overall incidence of intraoperative seizures was 2.3%. Independent risk factors for intraoperative seizures were seizure history, diagnosis of intracranial tumor, and temporal craniotomy. Intraoperative prophylactic anticonvulsant use was protective.