Intraoperative electrocorticography-guided glioma surgery: impact on extent of resection and functional preservation.

OBJECTIVE: Direct cortical stimulation (DCS) remains the gold standard for functional mapping in glioma surgery; however, its reliability may be limited by glioma-induced neural remodeling, incomplete motor mapping, and intraoperative constraints. We investigated whether supplementing DCS with electrocorticography (ECoG) for intraoperative functional mapping and tumor boundary delineation improves extent of resection (EOR) and neurological outcomes in glioma surgeries. METHODS: We conducted a single-center retrospective cohort study of 120 adults with supratentorial gliomas who underwent surgery between June 2021 and April 2024. Patients underwent awake or general anesthesia craniotomy with intraoperative mapping using DCS alone or DCS combined with ECoG. They were stratified into four groups: AC-ECoG (awake with DCS only, n=34), AC+ECoG (awake with DCS+ECoG, n=30), GA-ECoG (general anesthesia with DCS only, n=28), and GA+ECoG (general anesthesia with DCS+ECoG, n=28). Intraoperative ECoG was used for both functional mapping and tumor delineation. Multivariable linear regression evaluated ECoG's independent effect on EOR and 6-month outcomes (KPS, MoCA, MMSE), adjusting for tumor characteristics and patient factors. Descriptive subgroup analyses compared outcomes across anesthesia and mapping modalities. RESULTS: ECoG independently predicted higher EOR (β=3.3, p<0.001) and 6-month KPS (β=5.1, p=0.025), MoCA (β=1.8, p=0.003), and MMSE (β=3.0, p=0.024). Higher Ki-67 (≥10%) predicted lower EOR (β=-2.0, p=0.024). Subgroup analyses further demonstrated this effect, with ECoG-guided surgeries achieving higher EOR, smaller residual volumes, and improved early cognitive outcomes. CONCLUSION: Intraoperative ECoG independently improves extent of resection and early functional outcomes across anesthesia paradigms, supporting its role as a valuable adjunct to DCS in glioma surgery.