# Voxel-based mapping of postoperative epilepsy risk in glioma patients: supplementary motor area and limbic system correlations

## TL;DR

This study identifies brain regions where gliomas increase the risk of postoperative epilepsy, focusing on the supplementary motor area and limbic system.

## Contribution

The study introduces a voxel-based mapping method to identify glioma locations correlated with postoperative epilepsy risk.

## Key findings

- Epilepsy-susceptible regions are in the left medial frontal lobe's supplementary motor area.
- The anterior upper cingulate gyrus shows lower epilepsy risk in glioma patients.
- Gliomas in the anterior cingulate gyrus are associated with reduced postoperative epilepsy risk.

## Abstract

This study aims to explore the correlation between glioma location in the limbic system and the risk of secondary epilepsy.

This retrospective study included 170 cases of lower-grade gliomas treated with initial surgery from July 2007 to July 2019, sourced from the Chinese Glioma Genome Atlas (CGGA) database (http://www.cgga.org.cn). Patients were categorized into epilepsy and non-epilepsy groups based on postoperative symptoms. Imaging data were obtained from the Imaging Center of Beijing Tiantan Hospital, and postoperative epilepsy episodes were collected through follow-up. T2-weighted (T2WI) DICOM raw image data were converted into NII images, and tumor-susceptible regions were delineated using MRIcro software. Standardized T2WI gliomas and regions of interest (ROI) were analyzed using voxel-based lesion-symptom mapping (VLSM) software (https://crl.ucsd.edu/?). Overlapping ROIs were mapped for each patient. For voxel analysis in epilepsy-susceptible regions, the voxel with the highest t-value was defined as the peak voxel (PV). If the ROI overlapped with this voxel, the glioma was considered to confer a higher risk of epilepsy at that location. Statistical analysis was conducted using SPSS to compare glioma involvement in limbic system regions identified in imaging reports with patients’ postoperative epilepsy history.

Voxels significantly associated with tumor-related epilepsy were primarily located in the medial frontal lobe’s supplementary motor area of the left hemisphere. The peak voxel at this location was X = 88, Y = 155, Z = 134 (tmax = 4.69, p = 0.041), indicating the highest correlation with tumor-related epilepsy. Conversely, voxels less sensitive to epilepsy were mainly in the upper anterior cingulate gyrus. The peak voxel for this region was X = 91, Y = 166, Z = 79 (tmax = 3.70, p = 0.857), indicating the lowest correlation with tumor-related epilepsy.

Epilepsy-susceptible regions of tumor-related epilepsy are located in the supplementary motor area of the medial frontal lobe in the left hemisphere. Regions not susceptible to epilepsy could primarily be in the anterior upper cingulate gyrus. Gliomas involving the anterior cingulate gyrus in the limbic system are associated with a lower postoperative risk of tumor-related epilepsy.