Application of direct electrical stimulation in awake craniotomy for glioma resection in the motor area

Abstract

Objective To explore the effect of direct electrical stimulation in awake craniotomy for glioma resection in the motor area. Methods We conducted a retrospective analysis of clinical data of 34 patients with gliomas in the motor area who were admitted to Department of Neurosurgery, General Hospital of Southern Theatre Command from March 2015 to July 2017. The tumor was located in the left hemisphere in 16 patients and right hemisphere in 18. The gliomas were in supplementary motor area or premotor cortex in 23 cases, the central area in 9 cases, and supplementary motor area or premotor cortex invading the central area in 2 cases. All patients underwent awake craniotomy under general anesthesia. Neuronavigation and/or intraoperative ultrasound were employed to locate the lesion. Direct electrical stimulation was used for cortical and subcortical mapping of the important eloquent areas. The tumors were removed according to the functional boundary.Neural function and the degree of tumor resection were evaluated after operation. Results Of the 34 patients, 24 had a motor response after direct cortical electrical stimulation, 13 had abnormal sensations, and 10 revealed language-related cortices through mapping. For subcortical electrical stimulation, there were 24 cases of motor response, 1 case of abnormal sensation, and 8 cases of language disorders. A total of 30 cases (88.2%) of tumor removal reached functional boundaries, and subcortical electrical stimulation did not identify functional fiber in the remaining 4 (11.8%) cases which were all high-grade gliomas. Within 48 hours post surgery, the head MRI indicated total resection of tumor in 22 cases (64.7%), subtotal resection in 9 (26.5%), and partial resection in 3 (8.8%). The follow-up time of 34 patients was (23.6 ± 8.6) months (11.3-39.3)months.There were 29 cases (85.3%) which showed early postoperative neurofunctional disorders or worsening of pre-existing neurological deficits. Three cases (8.8%) developed late postoperative neurological dysfunction worse than preoperative conditions, of which 1 case was mild, 1 case was moderate and 1 case (2.9%) was severe. Of the 16 patients with preoperative neurological dysfunction or increased intracranial pressure, 13 had improved neurological function in 3 months after surgery, 2 were maintained in preoperative state and 1 had severe neurological deficits. Conclusions Functional mapping through direct electrical stimulation and continuous monitoring of the cortical and subcortical white fibers in the motor area during awake craniotomy could maximize the safe resection of glioma in the motor area, the incidence of long-term severe neurological deficits is low, and the quality of life could be improved after surgery. Key words: Glioma; Motor area; Supplementary motor area; Pyramid tract; Direct electrical stimulation