Standardized Localization of Intraoperative Direct Electrical Stimulation Sites in Awake Brain Surgery Using MRI-Based 3D Cortical Mapping

Objective: Intraoperative direct electrical stimulation (DES) remains the gold standard for mapping motor and cognitive cortical functions during awake brain surgery. However, a reproducible method to relocate these stimulation sites on the common brain template is still lacking, hindering reproducibility and data integration. Here, we propose our tested corticotopography method, as a reliable technique for mapping cortical DES sites onto brain atlases. Methods: Corticotopography was applied by matching the intraoperative image of the exposed cortex with the preoperative 3D MRI-based brain reconstruction using anatomical landmarks (i.e., sulci, gyri, and cortical vessels). Coordinates of the stimulation sites were then extracted using FSLeyes and mapped to MNI152 space. The method’s reliability was then evaluated through an inter-rater comparison. Lesion volume, tumor relapse status, and extent of craniotomy were tested for their potential bias on localization reliability. Results: Ninety eloquent cortical sites were identified in 19 patients undergoing awake surgery for glioma resection. Inter-rater analysis showed high concordance with 87% of stimulated sites presenting a spatial discrepancy below 2.5 mm. No significant differences in localization agreement were observed between newly diagnosed or relapsing tumors or as a function of lesion volume or craniotomy size. Conclusions: We introduce a standardized and reproducible corticotopography technique to localize intraoperative cortical stimulation sites on preoperative anatomical MRI. By formalizing the procedure used to map cortical functions, this method reduces inter-study variability, enabling DES to serve as a cumulative and interoperable resource for functional brain mapping. This allows cortical DES-derived information to be integrated with other neuroimaging modalities and leveraged across neuroscientific domains, including large-scale brain mapping and connectomics.