A Systematic Review and Meta-Analysis to Compare the Diagnostic Accuracy of Direct-Waves and Myogenic Motor-Evoked Potential Neuromonitoring During Intramedullary Spinal Cord Tumor Resection.

Background And Objectives: Intramedullary spinal cord tumor (IMSCT) resection seeks to maximize tumor removal while preserving neurological function, guided by intraoperative neurophysiological monitoring with myogenic motor-evoked potentials (myogenic MEPs) and direct waves (D-wave) recordings. Despite their widespread use, no systematic review has compared their accuracy for predicting immediate, transient, and persistent postoperative motor deficits in IMSCT surgery. This meta-analysis fills this gap by evaluating their diagnostic accuracy.

Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Diagnostic Test Accuracy guidelines, we analyzed 26 studies (1985-2024) involving 1079 patients with IMSCT with myogenic MEP and/or D-wave monitoring. Diagnostic performances were calculated with a bivariate model.

Results: For immediate postoperative motor deficits, myogenic MEPs demonstrated higher sensitivity with a log diagnostic odds ratios (log DOR) of 2.91 (95% CI: 2.15-3.67; area under the curve [AUC] 86.1%) compared with D-wave's log DOR 2.00 (95% CI: 0.96-3.04; AUC 77.7%). For transient motor deficits, myogenic MEPs also outperformed D-wave, achieving a log DOR of 1.94 (95% CI: 0.85-3.04; AUC 74.8%) vs D-wave's 0.68 (95% CI: -1.02 to 2.37; AUC 57.4%). For persistent motor deficits, myogenic MEPs maintained higher sensitivity with a robust log DOR of 1.89 (95% CI: 1.22-2.56; AUC 76.7%) and identified 23.1% of cases missed by D-wave in a cohort of 96 dual-monitored patients. However, D-wave showed a superior log DOR of 3.98 (95% CI: 2.55-5.40; AUC 93.4%), underpinned by exceptional specificity.

Conclusion: Myogenic MEPs and D-wave monitoring play complementary roles in IMSCT resection, requiring appropriate emphasis to optimize resection and neurological outcomes. Consistent with previous studies, myogenic MEPs showed high sensitivity in detecting transient motor deficits, whereas D-wave monitoring remained the most accurate predictor of persistent motor deficits. Our findings further suggest that myogenic MEPs contribute to identifying persistent motor deficits, challenging traditional views on their role. This association, although requiring prospective validation, highlights the need to interpret significant myogenic MEP changes carefully.