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A Systematic Review to Assess the Diagnostic Performance and Clinical Utility of Intraoperative Neuromonitoring
Ahsan Zil-E-Ali1, Noor Fatima2, Ibrahim Zulfiqar Ali2
1Division of Vascular Surgery, Heart and Vascular Institute, Pennsylvania State Milton S. Hershey Medical Center, Hershey, PA.
Background:
Intraoperative neuromonitoring (IONM), most commonly using electroencephalography (EEG) and somatosensory evoked potentials (SSEP), is increasingly used during carotid revascularization to detect cerebral hypoperfusion and acute neurologic compromise. However, evidence regarding its diagnostic accuracy, clinical utility, and impact on intraoperative decision-making, particularly during transcarotid artery revascularization (TCAR) remains limited. This systematic review evaluates the diagnostic performance and clinical relevance of IONM during carotid revascularization procedures.
Methods:
A systematic literature search was conducted across PubMed, Scopus, and the Cochrane Central Register of Controlled Trials to identify studies reporting the use of IONM during carotid revascularization. Data extraction focused on neuromonitoring modality, incidence of monitoring alerts, correlation with neurologic outcomes, intraoperative interventions, and diagnostic accuracy metrics, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value. Risk of bias was assessed using the Newcastle-Ottawa Scale.
Results:
Five retrospective studies encompassing 709 patients undergoing TCAR with IONM were included. Across studies, IONM demonstrated sensitivity up to 100% and NPV up to 100% for detecting immediate postoperative neurologic deficits. PPV varied by modality and alert definition but was highest when simultaneous EEG and SSEP changes were observed. The overall incidence of new neurologic deficits was low (0.4-3.4%). Unresolved perfusion-related IONM alerts were associated with a higher risk of immediate postoperative neurologic deficits, whereas most alerts resolved following intraoperative interventions such as blood pressure augmentation, clamp removal, or flow reversal adjustment. Studies employing transcranial Doppler and near-infrared spectroscopy consistently demonstrated transient reductions in cerebral blood flow and oxygenation during flow reversal, with recovery following restoration of antegrade flow.
Conclusion:
IONM during carotid revascularization, particularly TCAR, demonstrates excellent sensitivity and NPV for detecting cerebral hypoperfusion and neurologic compromise. Although its PPV is limited by the low incidence of neurologic events, multimodal monitoring, especially combined EEG and SSEP, enhances diagnostic reliability and supports timely intraoperative intervention. Prospective studies with standardized monitoring protocols are needed to define the optimal role of IONM and its impact on clinical outcomes.
