Intraoperative neuromonitoring during resection of cranial meningiomas and its effect on the surgical workflow.

Purpose: Resection of meningiomas adjacent to the central sulcus entails a high rate of morbidity. Explored for intra-axial lesion resection, intraoperative neuromonitoring intraoperative neuromonitoring (IONM) has been shown to decrease neurological deficits. The use of IONM is relatively uncommon and is not considered routine practice in the removal of extra-axial lesions. We sought to characterize IONM's impact on the surgical workflow in supratentorial meningiomas.

Methods: We retrospectively analyzed a prospectively collected database, searching cases in which IONM was used for resection of meningioma between 2017 and 2020. We classified the IONM effect on surgical workflow into 5 distinct categories of workflow changes (WFC).

Results: Forty cases of meningiomas with IONM use were identified. In 1 case (class 1 WFC), the operation was stopped due to IONM input. In 5 cases (class 2 WFC), the tumor was incompletely resected due to input from the IONM. In 14 cases (35%), IONM leads to an alteration of the resection process (alteration of approach, class 3 WFC). In 4 cases (10%), anesthesia care was modified based on IONM input (class 4 WFC). In 16 cases, no changes were made (class 5 WFC). In all patients in whom a change was made (24 cases, WFC 1-4), only 8.3% suffered a temporary deficit, and there were no permanent deficits, whereas when no change was made, there were 18.75% temporary deficit and 6.25% permanent deficit.

Conclusion: IONM has an impact during resection of meningiomas in eloquent areas and may guide the surgical technique, approach to tumor resection, and extent of resection.