Evaluating the predictive value of multimodal intraoperative neuromonitoring in anterior cervical discectomy and fusion: a retrospective cohort study on 442 patients

Background and objectives: Anterior cervical discectomy and fusion (ACDF) is a widely regarded surgical technique for the management of cervical disc herniation (CDH) and myelopathy, offering significant therapeutic efficacy. However, the potential for neurological complications persists, underscoring the need for strategies to enhance procedural safety. Multimodal intraoperative neuromonitoring (IONM) has emerged as a promising adjunct, providing real-time assessment of neural integrity to identify and address intraoperative compromise. This study seeks to rigorously assess the diagnostic accuracy of IONM in ACDF, evaluate its predictive utility for postoperative neurological outcomes, and analyze its association with intraoperative neural events. Methods: This monocentric retrospective observational study analyzed CDH patients who underwent ACDF between 2014 and 2023. Neurological status was pre- and postoperatively assessed and compared to IONM data, including somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs), and electromyography (EMG) alarms. IONM diagnostic performance was analyzed using confusion matrices and ROC curves on the binary variables. Multivariate logistic regression was implemented to identify predictors of postoperative neurological decline. Results: SSEPs and MEPs demonstrated high diagnostic accuracy, with ROC curve areas improving significantly from preoperative (T0) to postoperative (T1) assessments (SSEP AUC: 0.922 to 1.000; MEP AUC: 0.915 to 0.996, p < 0.01). Among 442 consecutive patients, 38 (9%) intraoperative IONM alerts were recognized, labeled as transient, sustained single-modality, or sustained dual-modality changes. Permanent neurological injuries correlated with alert severity. Intraoperative alarms were the strongest predictor of postoperative motor deficits (OR:14.0, p < 0.01). Conclusion: Multimodal IONM demonstrated significant predictive value for postoperative neurological outcomes in ACDF, with intraoperative alerts strongly correlating with motor deficits. IONM was associated with postoperative neurological outcomes, suggesting a potential role in selected high-risk patients. Further studies are warranted to assess cost-effectiveness and define standardized indications.