The Role of D-Wave Monitoring in Motor-Evoked Potential Loss During Intramedullary Spinal Cord Tumors Resection

Objective Motor-evoked potential (MEP) loss during intramedullary (IM) spinal cord tumor surgery impairs the ability to monitor further neural injury. Direct wave (D-wave) monitoring may allow continued assessment of corticospinal tract integrity after MEP loss. This study evaluates the role of D-wave-guided surgery in preserving function and enabling safe resection after MEP loss. Methods A retrospective study was conducted in adult patients with ependymoma (EPN), cavernous angioma (CA) or subependymoma who experienced MEP loss during IM tumor resection between January 2012 and May 2025. Patients who underwent continued resection under D-wave guidance after MEP loss were compared with those who did not. Results Among 37 eligible patients, 9 underwent D-wave-guided surgery and 28 did not. Functional improvement at the last follow-up was more frequent in the D-wave-guided surgery group (66.7% vs. 17.9%, p=0.011). This trend remained significant in EPN patients (74.4% vs. 9.1%, p=0.003), but not in CA patients. Immediate postoperative motor grade ≤3 was more common in the D-wave-guided surgery group (66.7% vs. 39.3%), although this difference was not statistically significant (p=0.251). By last follow-up, the proportions of patients self-ambulatory without external aids (88.9% vs. 89.3%, p=1.000) were similar between groups. Extent of resection, complications, and recurrence rates showed no significant differences. Conclusion D-wave-guided surgery may enable safe continuation of tumor resection after MEP loss without increasing morbidity. It offers a viable intraoperative strategy to preserve long-term motor function by extending monitoring beyond MEP limitations.