Arcuate fasciculus cortico-cortical and axono-cortical evoked potentials with post-resection excitability changes in perisylvian glioma.

Objective: To evaluate the feasibility and clinical utility of arcuate fasciculus cortico-cortical evoked potentials (AF-CCEP) and axono-cortical evoked potentials (AF-ACEP) during perisylvian supratentorial tumor surgery, and examine whether morphology changes serve as electrophysiological biomarkers of postoperative language function. Methods: We analysed 19 patients with tumors involving or adjacent to the arcuate fasciculus across multiple tertiary centers. AF-CCEPs were elicited by monophasic stimulation toward the inferior frontal gyrus and recorded over the middle or posterior superior temporal gyrus; AF-ACEPs were obtained via subcortical bipolar stimulation. Primary outcomes explored N1 morphology pre- and post-resection, with subgroup analyses by tumor grade, location, montage, and anesthesia. Results: 822 AF-CCEPs and 134 AF-ACEPs were acquired intraoperatively; 133 and 37 matched recordings were included for analysis, respectively. Post-resection N1 peak amplitude increased cohort-wide, while onset latency remained stable. One patient demonstrated signal loss associated with postoperative aphasia. AF-ACEP amplitudes were higher under general anesthesia, in higher-grade tumors, and with proximity to the AF on tractography. Conclusions: AF-CCEP and AF-ACEP are feasible intraoperative adjuncts, with signal degradation associated with language morbidity. Post-resection amplitude increases may reflect intact AF conduction with increased cortical excitability following tumor removal. Significance: When awake craniotomy is contraindicated, AF-CCEP and AF-ACEP may represent a viable alternative for monitoring AF integrity and reducing postoperative language morbidity.