Introduction: Cervical spondylotic myelopathy (CSM) is a progressive and debilitating pathology characterized by spinal cord injury secondary to degenerative changes, often resulting in neck pain, sensory and motor deficits, limited ambulation, and decreased ability to perform activities of daily living. Intraoperative neurophysiologic monitoring is often viewed as a standard adjunct in the operative treatment of CSM.
Methods: A retrospective analysis was conducted on 90 patients who underwent surgical treatment for CSM. TcMEP amplitude and AUC were analyzed for different areas. Functional outcomes were assessed using Odom criteria, Nurick score, and mJOA score at immediate postoperative, 6, and 12 month. Mixed effects models analyzed the impact of TcMEP changes on Odom scores. Additionally, univariate linear regression analyses were performed to examine relationships between changes in TcMEP measurements and postoperative functional outcomes.
Results: Patients with postoperative decreases in left deltoid amplitude and AUC had significantly worse Odom scores at 6-month follow-up compared to those with amplitude and AUC increases (p=0.016, η²=0.14; p=0.021, η²=0.14). A ≥50% increase in left deltoid AUC was associated with significantly better Odom scores at 6 months (p=0.044, η²=0.07). Improvements in left APB-ADM strength were associated with better postoperative outcomes as measured by Odom's Criteria (coefficient = 0.023, p = 0.009). Improvements in right deltoid strength were associated with better outcomes at 6 months as measured by Odom's Criteria (coefficient = 0.020, p = 0.019). Furthermore, improvements in right APB-ADM strength were associated with better outcomes at 12 months as measured by the Nurick Score (coefficient = -0.019, p = 0.043), and improvements in right AH-ADQ strength were associated with better outcomes at 6 months as measured by the Nurick Score (coefficient = -0.019, p = 0.035).
Conclusion : In CSM patients, postoperative decreases in left deltoid TcMEP amplitude and AUC are associated with worse functional recovery at 6-month follow-up. A ≥50% increase in left deltoid AUC may predict 6-month functional improvement. Additionally, changes in various muscle group strengths show significant associations with functional outcomes at different time points.
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