Abstracts

Rationale: The yield of post-operative continuous EEG monitoring (cEEG) after tumor resections with cortical stimulation have not been evaluated or described in the literature. The goal of this study is to better understand the timing of post-operative seizures and identify factors associated with post-operative seizures in patients who have undergone tumor resection with intraoperative cortical stimulation.Methods: The Northwestern Memorial Hospital intraoperative monitoring database was searched for patients undergoing intraoperative cortical stimulation during resective surgery. A total of 133 patients were identified from 2013-present with 16 patients identified that had post-operative seizures after undergoing cortical stimulation. Data regarding clinical history, tumor type, electrocorticography results, timing of EEG and post-operative seizures was collected and analyzed.Results: Of a total 133 patients with cortical stimulation during surgical resection, 16 patients were found to have post-operative seizures (12.0%) during their hospitalization. There was no statistically significant association between the presence of intraoperative after-discharges or seizures and the occurrence post-operative seizures (p=0.865) More than 2/3 of seizures were found to occur between days 2-4 with the majority occurring on post-op day 3 (31.3%). The majority of patients were connected to cEEG monitoring on post-op day 3 (31.3%). Half of patients with post-operative seizures were found to be in status epilepticus, with 75% of those patients having clinical accompaniments to the status epilepticus and the remaining with no clinical features.Conclusions: Earlier studies have found the incidence of seizures after brain surgery to be around 8%.1 Based on the findings of this study, there appears to be a potential increased risk for seizures after cortical stimulation (12%). Seizures most commonly occur 2-4 days after surgery, with the peak incidence on post-operative day 3. Half of patients with post-operative seizures after cortical stimulation have status epilepticus. While the majority of seizures had clinical signs, this may be in part due to the population selected for cEEG monitoring rather than a true reflection of the frequency of seizures in this population. Physicians should be cognizant of the risk of post-operative seizures in patients who have had intraoperative cortical stimulation, specifically 2-4 days after surgery. 1 Wu AS, Trinh VT, Suki D, et al. A prospective randomized trial of perioperative seizure prophylaxis in patients with intraparenchymal brain tumors. J Neurosurg. 2013 Apr; 118(4): 873-83.