S125. Degree of resolution of neuromonitoring alerts predicts the likelihood of neurological deficits in extradural cervical spine surgery: Review of 30,921 procedures

Abstract

Introduction Multimodality intraoperative neuromonitoring (IONM) is frequently used during extradural spine surgery. Further understanding about the clinical significance of the reversibility of IONM alerts may provide guidance regarding the need to alter the intraoperative surgical technique. We asked whether the presence of an IONM alert, and the degree to which it resolved intraoperatively, predicted the likelihood of a postoperative neurological deficit. Methods We performed a retrospective review of a multi-institutional database to analyze a series of 30,921 consecutive extradural cervical spine procedures performed between October 2015 and October 2017 at 517 U.S. institutions. Within each case, the presence or absence of an IONM alert was recorded, as well as the degree of resolution at the conclusion of surgery for those cases with one or more alerts (fully resolved, partially resolved, unresolved). Presence or absence of a neurological deficit was recorded in the postoperative period. Relative odds of new-onset post-operative neurological deficit according to IONM alert resolution status were assessed using a random effects logistic regression model controlling for patient age, gender, number of vertebral levels addressed, surgical approach (anterior (A), posterior (P), or combined A/P), anesthesia regimen, trauma status, surgeon, surgical neurophysiologist, and hospital. Results There were 785, 497, and 2332 cases with no, partial, or full resolution of alerts, respectively. After controlling for all of the above named factors, we found that relative to cases with no IONM alerts, cases with alerts had significantly higher risk of neurologic deficit following an expected relative risk gradient. Cases with fully resolved IONM alerts were more than twice as likely to experience a deficit (OR = 2.5, 95%CI: 1.3–4.9, p Conclusion Degree of resolution of IONM alerts helps to predict the likelihood of a neurological deficit in the postoperative setting in patients undergoing extradural spine surgery. While risk of a neurological deficit is highest when alerts do not resolve, there is also a slightly increased risk of a neurological deficit with full resolution. Awareness of these relationships helps the surgical team make decisions intraoperatively, and allows the surgeon to counsel the patient.