Clinical impact of transcranial unilateral motor evoked potentials monitoring in cerebral aneurysm endovascular treatment.

OBJECTIVE

Neurosurgery commonly employs motor evoked potential (MEP) monitoring to assess intraoperative motor function. However, its utility in neuroendovascular procedures has been sporadically reported, widespread adoption remains limited, largely due to challenges associated with stimulus-induced patient movement and subsequent image misregistration. This study aimed to address these limitations by evaluating the feasibility of an optimized transcranial electrical stimulation MEP (TES-MEP) protocol designed to minimize body movement while preserving monitoring reliability.

METHODS

We performed a retrospective review of 62 aneurysms treated with endovascular coil embolization for cerebral aneurysms under total intravenous anesthesia (TIVA). We employed various TES-MEP montages, C3(±)-C4(∓), C1/C2(+)-C4/C3(-), C4/C3(+)-C1/C2(-), or C1(±)-C2(∓), specifically optimized to elicit a unilateral MEP and minimize body movement. We assessed stimulus-induced movement, the quality of MEP recordings, and intraoperative MEP changes.

RESULTS

MEPs were successfully obtained in all cases, with no procedures interrupted by patient movement. In contrast, conventional C3(±)-C4(∓) stimulation caused unacceptable movement in 29.3% of cases. Our modified montage facilitated stable monitoring, eliminating digital subtraction angiography (DSA) misregistration and the need for repeated imaging. Intraoperative MEP amplitude reductions occurred in two patients, both linked to ischemic events and prompting timely intervention.

CONCLUSIONS

Our TES-MEP monitoring method is feasible and safe in neuroendovascular procedures. By reducing procedure-disrupting movement while maintaining ischemia detection, the protocol improves workflow safety and holds meaningful potential to enhance patient outcomes. Given its retrospective design, the study is subject to inherent limitations, and prospective studies are warranted to validate these findings and further refine stimulation protocols.