Impact of intraoperative stimulation mapping on high-grade glioma surgery outcome: a meta-analysis

Background: Intraoperative stimulation mapping (ISM) using electrocortical mapping (awake craniotomy, AC) or evoked potentials has become a solid option for the resection of supratentorial low-grade gliomas in eloquent areas, but not as much for high-grade gliomas. This meta-analysis aims to determine whether the surgeon, when using ISM and AC, is able to achieve improved overall survival and decreased neurological morbidity in patients with high-grade glioma as compared to resection under general anesthesia (GA). Methods: A systematic search was performed to identify relevant studies. Adult patients were included who had undergone craniotomy for high-grade glioma (WHO grade III or IV) using ISM (among which AC) or GA. Primary outcomes were rate of postoperative complications, overall postoperative survival, and percentage of gross total resections (GTR). Secondary outcomes were extent of resection and percentage of eloquent areas. Results: Review of 2049 articles led to the inclusion of 53 studies in the analysis, including 9102 patients. The overall postoperative median survival in the AC group was significantly longer (16.87 versus 12.04 months; p < 0.001) and the postoperative complication rate was significantly lower (0.13 versus 0.21; p < 0.001). Mean percentage of GTR was significantly higher in the ISM group (79.1% versus 47.7%, p < 0.0001). Extent of resection and preoperative patient KPS were indicated as prognostic factors, whereas patient KPS and involvement of eloquent areas were identified as predictive factors. Conclusions: These findings suggest that surgeons using ISM and AC during their resections of high-grade glioma in eloquent areas experienced better surgical outcomes: a significantly longer overall postoperative survival, a lower rate of postoperative complications, and a higher percentage of GTR