# Postoperative Seizure in Patients with Malignant Glioma Undergoing Tumor Resection with Intraoperative Mapping: Risk Factors, Management Strategies, and the Utility of Bayesian Analysis in a Case-Control Cohort

## TL;DR

This study identifies risk factors for postoperative seizures in glioma patients undergoing brain surgery with intraoperative mapping and suggests strategies to reduce seizure risk.

## Contribution

The study introduces Bayesian analysis to assess seizure risk factors in glioma surgery with intraoperative mapping.

## Key findings

- A prior history of seizures increases the risk of postoperative seizures with 73% probability.
- Awake intraoperative mapping is protective against postoperative seizures with 88% probability.
- Intraoperative seizures during mapping correlate with an 84% probability of postoperative seizures.

## Abstract

Postoperative seizures can occur secondary to cortical irritation from malignant glioma resection or from direct electrical stimulation of the cortical surface during intraoperative brain mapping. A paucity of literature exists with regards to the use of appropriate seizure risk-reduction strategies for this patient population. The objective of the study was to identify primary risk factors for early and late postoperative seizures following intraoperative brain mapping.

The authors performed a case-control study with 30 patients who had postoperative clinical seizures within 6 months following craniotomies with intraoperative mapping for glioma resection from 2013 to 2021 at a single academic institution. An unmatched control population of all patients (n=52) who had undergone craniotomies with ICM during the same period and had no clinical seizures within 6 months following their operation were used for comparative analysis. Primary endpoint was any postoperative seizure within 6 months of surgery. Outcomes were analyzed both via frequentist and Bayesian statistical approaches.

Bayesian analysis using non-informative priors demonstrated that the probability of an odds ratio (OR) > 1 for prior history of seizures being a risk factor for postoperative seizures is 73%. The probability that OR < 1 for a patient with post op seizures who underwent motor mapping was 91%. If patients experienced an intraoperative seizure during mapping, the probability of having a postoperative seizure was 84%. Probability that awake mapping is protective of post op seizure when compared to asleep mapping is 88%. Complex anti-epileptic drug (AED) regimen (increasing dose + adding additional AEDs or 2 dose adjustments) had 64% probability of protection from late postoperative seizures.

Patients with a preoperative history of seizures may be at higher risk for postoperative seizures. More aggressive perioperative seizure prophylaxis may provide a protective benefit from postoperative seizures in patients who undergo intraoperative mapping.