Comparative diagnostic performance of motor-evoked potential alarm thresholds for predicting postoperative neurological decline in intradural extramedullary spinal tumor surgery: a systematic review and meta-analysis

Abstract

Variability in motor evoked potential (MEP) alarm thresholds limits interpretation of intraoperative monitoring during intradural extramedullary (IDEM) tumor surgery. We aimed to compare predefined MEP thresholds for predicting postoperative neurological decline. PubMed, Embase, and Cochrane were searched from inception to 9 November 2025 for studies evaluating MEP accuracy in predicting postoperative motor deficits. Studies assessing MEP within multimodal intraoperative neurophysiological monitoring (mIONM) for predicting neurological deficits were also analyzed. MEP thresholds and diagnostic contingency data were extracted. Sensitivity, specificity, positive and negative predictive values, and area under the receiver operating characteristic curve (AUROC) were calculated for complete MEP amplitude loss and 50%-, 70%-, and 80%-level MEP amplitude decline categories. AUROC confidence intervals and p-values were obtained using study-level bootstrap resampling when feasible. Sixteen studies were included. In separate-threshold MEP analyses, 50%-level, 70%-level, and complete MEP amplitude loss criteria significantly predicted short-term motor deficits, whereas 50%- and 70%-level thresholds significantly predicted long-term motor deficits. The 50%-level threshold showed the most favorable short-term profile, with 94.1% sensitivity and 98.4% specificity. In sensitivity analysis, the pooled 70%/80%-level high-threshold group also showed significant diagnostic performance for short- and long-term motor deficit prediction. Within mIONM, the 50%-level threshold showed the most favorable point estimates, although formal testing was unavailable for short-term performance. Significant mIONM diagnostic performance was shown for complete MEP amplitude loss in short-term evaluation and for the 50%-level threshold in long-term evaluation. The 50%-level MEP amplitude decline threshold showed the most favorable profile for short-term motor deficit prediction in MEP-based analyses and favorable estimates within mIONM. Higher thresholds retained diagnostic utility. These findings should be interpreted cautiously because of differences in sample size, tumor location, histology, and outcome reporting between threshold groups.