Background Intraoperative neuromonitoring (IONM) is often used during cerebral endovascular procedures.
Objective To investigate the relationship between intraoperative vascular complications and IONM signal changes, and the impact of interventions on signal resolution and postoperative outcomes.
Methods A series of 2278 cerebral endovascular procedures conducted under general anesthesia and using electroencephalography and somatosensory evoked potential monitoring were retrospectively reviewed. A subset of 763 procedures also included motor evoked potentials (MEPs). IONM alerts were categorized as either a partial attenuation or complete loss of signal. Vascular complications were subcategorized as due to rupture, emboli, instrumentation, or vasospasm. Odds ratios (ORs) for new postoperative motor deficits were calculated and diagnostic accuracy was measured using sensitivity, specificity, and likelihood ratios.
Results The overall incidence of new postoperative motor deficit was 1.2%; 20.4% in cases with an IONM alert and 0.09% in cases without an alert. Relative to procedures with no alerts, odds of a new deficit increased if there was partial signal attenuation (OR=210.9, 95% CI 44.3 to 1003.5, p<0.0001) and increased further with complete loss of signal (OR=1437.3, 95% CI 297.3 to 6948.2, p<0.0001). Relative to procedures with unresolved alerts, odds of a new deficit decreased if the alert was fully resolved (OR=0.039, 95% CI 0.005 to 0.306, p<0.002). Procedures using MEPs had slightly higher sensitivity (92.3% vs 85.7%) but slightly lower specificity (96.7% vs 98.2%).
Conclusions An IONM alert associated with an arterial complication is associated with a dramatic increase in odds of a new postoperative deficit; however, if there is resolution of the alert prior to closure, odds of a new deficit decrease significantly.
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Contributors WBW conceived the study and drafted/edited the manuscript. AKS drafted/edited the manuscript and provided critical data analyses. OB, and EK provided critical data analyses. SIT, MRG, PJ, RR, JDE, JC and WK provided critical manuscript edits and feedback. ET provided the statistical analyses.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests AKS notes stock ownership in KPSC Holdings/Specialty Care and has received honoraria from the American Society of Neurophysiological Monitoring and the Overlook Foundation. WK reports personal consulting fees from Stryker Neurovascular, small stock option interest in Route 92 Medical, outside the submitted work; In addition, WK has a patent with Route 92 Medical pending.
Patient consent for publication Not required.
Ethics approval The current study was approved by SpecialtyCare IOM Services IRB# CR00183489. Because this study was a retrospective review of data from a de-identified multi-institutional operative procedure database and had no identifiable patient data in the manuscript, patient consent was not required.
Provenance and peer review Not commissioned; externally peer reviewed.