Intraoperative motor evoked potential changes associated with surgical trajectory adjustment during endoscopic evacuation of basal ganglia hemorrhage: A technical note with illustrative case.

BACKGROUND: Endoscopic evacuation has become an important minimally invasive strategy for hypertensive intracerebral hemorrhage. However, hematomas located in the basal ganglia are frequently adjacent to the corticospinal tract, placing motor pathways at risk during surgical manipulation. Intraoperative neurophysiological monitoring, particularly motor evoked potentials (MEPs), may provide real-time functional feedback during surgery. CASE DESCRIPTION: A 45-year-old man presented with acute right hemiplegia. Computed tomography revealed a left basal ganglia hemorrhage (~35 mL). Endoscopic hematoma evacuation was performed under continuous MEP monitoring. During sheath advancement and clot removal, a marked reduction in MEP amplitude (approximately 25-30%) was observed on the affected side. Surgical manipulation was immediately paused, and the trajectory was slightly adjusted. MEP signals subsequently recovered toward baseline levels. Postoperative CT confirmed >90% hematoma evacuation. At 3-month follow-up, the patient achieved a modified Rankin Scale score of 2 with improved motor function. CONCLUSION: This illustrative case suggests that real-time MEP monitoring may provide adjunctive intraoperative information without spatial localization of the underlying anatomical structures during endoscopic evacuation of basal ganglia hemorrhage. Transient signal deterioration may be temporally associated with surgical manipulation and may prompt reassessment of the surgical corridor.