Visualizing intraoperative transcranial motor-evoked potentials during glioma surgery for predicting postoperative paralysis prognosis.

Purpose: The primary goals of glioma surgery are maximal tumor resection and preservation of brain function. Intraoperative motor-evoked potential (MEP) monitoring is commonly used to predict and minimize postoperative paralysis. However, studies on intraoperative MEP trends and postoperative paralysis are scarce. This study aimed to determine the relationship between intraoperative MEP trends and postoperative paralysis.

Methods: This retrospective study evaluated 229 patients with supratentorial glioma without preoperative paralysis who underwent tumor resection surgery under general anesthesia at our institution between October 2019 and December 2022. Intraoperative transcranial MEP monitoring was performed, and the entire MEP trends on affected and unaffected sides was visualized. Postoperative paralysis and patient-related factors were analyzed.

Results: Postoperative paralysis occurred in 36 patients, with the paralysis improving over time and being permanent in 30 and 6 patients, respectively. In the improvement group, the temporary decrease in transcranial MEP rapidly improved. Even when the MEPs were <50% of the control value, fluctuations indicating improvement were observed after the decrease. However, in the permanent paralysis group, transcranial MEP remained consistently <50% of the control value until the end of surgery, after its initial decrease. The significant factors contributing to permanent paralysis were tumor localization close to the pyramidal tract (p = 0.0304) and postoperative cerebral infarction in the pyramidal tract (p = 0.0009).

Conclusions: The overall intraoperative MEP trend can reflect the risk of postoperative paralysis during glioma surgery. Thus, visualizing this trend can provide a better understanding of the prognosis of postoperative paralysis.