Intraoperative Neurophysiologic Monitoring Improves Neurologic Outcomes in Eloquent Brain Areas and Aids in Increasing the Volume of Resected Glioma: Current Results Compared With Historical Controls.

Purpose: This study aims to show the impact of multimodal intraoperative neurophysiologic monitoring (IOM) in glioma surgery in preventing severe neurologic injury and increasing tumor removal by comparing the historical cases where IOM was not used.

Methods: Fifty-nine patients with glial tumors located nearby the eloquent area, operated by the same surgeon, were included in the study. Between 2008 and 2012, 21 patients were operated on without IOM (non-IOM); between 2018 and 2021, 38 patients were operated on with IOM.

Results: The preoperative Karnofsky performance status scale (KPSS) scores were not statistically significant between non-IOM and IOM groups (P = 0.351). Postoperative KPSS (mean 97.9) scores were 15.7% higher than preoperative KPSS (mean 84.6) in the IOM group (P < 0.001). Conversely, there was no significant difference between preoperative and postoperative KPSS scores (mean 78.5 and 81.5, respectively) in the non-IOM group (P = 0.472). Moreover, postoperative KPSS scores were 20% higher in the IOM group than in the non-IOM group (P < 0.001). Preoperative tumor sizes were double the size in the non-IOM group compared with those in the IOM group (P = 0.007). Nevertheless, the postsurgery tumor residue volume was almost four times higher in the non-IOM group than that in the IOM group (P = 0.035). A median of 93.35% of the tumor volume was resected in the IOM group, but only 77.26% of the tumor was removed in the non-IOM group (P < 0.001).

Conclusions: Intraoperative neurophysiologic monitoring helps in a more radical tumor resection in glial tumors located close to the eloquent area, improves postoperative neurologic outcomes, and maintains the patient's quality of life.