Assessing the Impact of Intraoperative Neuromonitoring Alerts on Postoperative Neurological Motor Outcomes in Spine Surgery

Introduction: Over the past decade, there has been an increase of 296% in intraoperative neuromonitoring (IONM) usage. However, the current literature has shown mixed results regarding the correlation between alerts and post-operative neurological outcomes. Some literature suggests that alerts help mitigate procedure risks. Other literature reports indicate alerts are associated with post-operative neurological deficits. This study aimed to identify patient and procedure characteristics associated with IONM alerts and predictors of decreased motor function postoperatively.

Methods: Medical records of patients at a single institution who had a documented preoperative motor neurological exam and underwent spine procedures with IONM over four years (May 2018-February 2023) were reviewed. Variables reviewed included patient demographics; type, location, and approach of spine procedure; number of levels decompressed and/or fused; preoperative motor exam findings; duration of surgery; and presence of IONM alerts. Outcomes assessed were postoperative exam findings and duration of hospital stay.

Results: 76 IONM alerts were identified in 764 patients. IONM alerts were significantly associated with male sex (p = 0.001), longer operative times (p = 0.001), surgeries involving only decompression (p = 0.02), and patients with new onset motor deficits on postoperative day 1 (p = 0.03), but not with duration of hospital stay. Independent predictors of postoperative motor deficits included increased surgical time (multivariate p = 0.001) and non-cervical procedures (multivariate p = 0.03).

Conclusion : Although IONM may be a beneficial tool for surgical safety enhancement, there are challenges with the interpretation and reaction to alerts. This study highlights that IONM has limitations since alerts do not always correlate with postoperative deficits. However, there is a role for further investigation regarding targeted application of IONM in high yield procedures. Data suggest that IONM may be useful for longer and non-cervical spine procedures.