Implementation of cortical and subcortical stimulation techniques in patients with gliomas in the speech-dominant cerebral hemisphere during awake craniotomy procedures

Background. The application of cortical and subcortical stimulation during awake craniotomy mitigates the risk of persistent postoperative speech deficits. However, the functions of some white matter pathways remain inadequately understood, particularly the frontal aslant tract (FAT) of the dominant hemisphere.

Aim. To evaluate the efficacy of cortical and subcortical stimulation techniques in the localization of glial tumors near speech centers and pathways (SLF / AF, FAT, IFOF) within the context of awake surgery.

Materials and methods. A cohort of 17 patients (6 males, 11 females) underwent surgical intervention using intraoperative awakening technique at the Federal Neurosurgical Center in Novosibirsk between 2020 and 2023. Comprehensive assessments of neurologic and neurolinguistic status were conducted preoperatively, postoperatively, and during follow-up. Additionally, MR-tractography was performed. Tract reconstruction and tumor volumetry were performed using semi-automatic segmentation methods on the BrainLab workstation.

Results. Employing subcortical bipolar stimulation and continuous monopolar stimulation, the mean extent of resection (EOR) achieved was 89.3 % (IQR = 26, Q1 = 74, Q3 = 100). Transient speech deficit manifested in 10 out of 17 patients (59 %). In these cases, the white matter tracts (SLF / AF, FAT, IFOF) were either contiguous with the tumor or within a distance of 4 mm from it. Speech impairments resolved within the first three months post-surgery, with only one patient exhibiting persistent neurologic deficit.

Conclusion. The implementation of cortical and subcortical stimulation (monopolar and bipolar) in the surgical resection of glial tumors in the speech dominant hemisphere demonstrates a high degree of radical resection while minimizing the incidence of persistent postoperative speech deficits. Transient postoperative speech disturbances were observed in all patients whose preoperative tractography indicated that associative tracts (SLF / AF, FAT, IFOF) were located within 4 mm from the tumor margin.

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