Does Resolution of Neuromonitoring Alerts Impact Weakness or Short-Term Outcomes?

Introduction: Intraoperative neuromonitoring is a necessary tool to track spinal cord function during spine surgery with alerts indicating reduced nerve output and input. This allows the surgeon and anesthesiologist to alter positioning and technique to bring back appropriate nerve signaling. This study analyzes the impact that resolution of these alerts has on postoperative outcomes.

Methods: All adult patients who had a spinal fusion with intraoperative neuromonitoring resulting in an alert in 2017 at an urban tertiary center were included. Exclusion criteria were intraoperative mortality and lack of notated pre- and postoperative physical exams. Weakness/deficit was classified as ≤3/5 and a drop of ≥1 for either postoperative timepoint (immediately postoperative and two-week clinical visit) compared to preoperative strength. This was further categorized into any deficit, immediate deficit only (weakness resolved by two-week clinical visit), persistent deficit (not resolved by two-weeks), and de novo two-week (weakness only at two-weeks). Neuromonitoring resolution was determined as full (resolved to baseline), partial (improved from alert but not at baseline), and no resolution. Statistical analysis was performed using Kruskal-Wallis tests (alpha 0.05).

Results: 117 patients were included with similar demographics between patients who had no, partial, or full resolution. Partial and full resolution groups had a higher percentage of cervical region involvement (86.4% and 67.1% vs 25.0%, p< 0.001). Notably, there were no differences in type of deficit (any postoperative, immediate postoperative only, persistent postoperative, and de novo two-week only), complications, length of stay, discharge disposition, ED visits within 90 days, or readmissions within 90 days.

Conclusion : While intraoperative neuromonitoring plays a key role in spine surgery, this data suggests that once an alert is triggered its resolution is not associated with improved outcomes. As such, spine surgeons should proceed with additional caution knowing that damage may be more permanent than alert resolution indicates.