Systematic review of alarm criteria and reversibility in motor-evoked potentials during intramedullary spinal cord tumor resection.

BACKGROUND/

OBJECTIVE

Myogenic motor-evoked potentials (myogenic MEPs) and Direct waves (D-waves) are essential for monitoring motor pathways during intramedullary spinal cord tumor (IMSCT) resections. However, the diagnostic accuracy of alarm criteria and the prognostic value of reversible versus irreversible changes remain unclear. This is the first study addressing this gap.

METHODS

Following PRISMA-DTA guidelines, this review searched PubMed, MEDLINE, and OVID (1985-2024) for studies on intraoperative myogenic MEPs and/or D-waves with postoperative motor outcomes in IMSCT resections.

RESULTS

Across 25 studies (1,060 patients), log DOR for complete myogenic MEP loss predicting postoperative motor deficits was 4.18 (95% CI: 2.63-5.73), and for incomplete loss was 2.46 (95% CI: 1.74-3.18). Irreversible reductions had a log DOR of 2.513 (95% CI: 1.197-3.829), reversible 0.528 (95% CI: -0.273-1.330). D-wave monitoring used 50% threshold consistently, reversible reductions tied to 75% deficit rate.

CONCLUSION/SIGNIFICANCE: Irreversible changes in myogenic MEPs and D-waves and reversible D-wave changes increased postoperative motor deficit risk, unlike reversible myogenic MEP changes. Additionally, both incomplete and complete myogenic MEP loss predict neurological deficits; however, complete loss is a stronger predictor than incomplete loss. These findings help neurophysiologists guide the surgical team in minimizing motor pathway injury while maximizing IMSCT resections.