To investigate the role of direct electrical stimulation under awake craniotomy in resection of diffuse lower-grade glioma in the eloquent brain areas.

A retrospective study was performed on the clinical data of 38 patients with diffuse lower-grade glioma located in supratentorial eloquent areas who were admitted to the Department of Neurosurgery of General Hospital of Southern Theater Command from February 2017 to July 2020. Among the patients, 9 had recurrent gliomas. All patients underwent awake craniotomy and direct electrical stimulation was performed to locate the cortical/subcortical important functional areas. The extent of excision and postoperative neurological dysfunction were documented.

After intraoperative direct electrical cortical stimulation, 31 cases (81.6%) showed positive response and 7 (18.4%) showed negative response. During subcortical stimulation, 25 cases (65.8%) showed positive response and 13 cases (34.2%) showed negative response. Both cortical and subcortical electrical stimulations induced negative response in 5 cases (13.2%). Total resection was achieved in 21 cases (55.3%), including 5 cases with supratotal resection. Subtotal resection was performed in 13 cases (34.2%) and partial resection in 4 cases (10.5%). A total of 26 cases (68.4%) had new or aggravated neurological dysfunction within 3 months after surgery and 4 cases (10.5%) had irreversible mild-moderate neurological dysfunction after 3 months. Of the 9 recurrent patients, 8 cases underwent resection reaching the boundary of eloquent areas. There were 2 cases who developed mild newly-onset neurological dysfunction at 3 months post operation.

Brain functional mapping using direct cortical electrical stimulation in awake craniotomy can maximize the extent of safe resection of diffuse lower-grade glioma in the eloquent brain areas and help reduce the incidence of postoperative neurological dysfunction.

Glioma; Electric stimulation; Neurophysiological monitoring; Eloquent brain regions; Awake craniotomy