Intraoperative neuromonitorig alert risks in patients submitted to anterior cervical decompression and fusion for cervical spondylotic myelopathy: a single institution cohort-study.

PURPOSE: To identify positional and intraoperative significant multimodal intraoperative neurophysiological monitoring (mIONM) alert risk factors during anterior cervical surgery in patients with cervical spine myelomalacia.

METHODS

We analyzed prospectively collected data from the PANDA registry between January 2021 and February 2025. Included were patients undergoing anterior cervical decompression and fusion with MRI-confirmed myelomalacia. A significant alert was defined as a ≥ 50% reduction in MEP and/ SSEP amplitude, a ≥ 10% increase in MEP latency, or a spEMG signal. Patients were categorized into three groups: significant warnings at positioning (Group A), during surgical decompression (Group B), and no significant warnings (Group C). Nineteen anamnestic, clinical, radiological, and surgical factors were evaluated. A standardized anesthesia protocol and alert-response strategy were applied.

RESULTS

Seventy-six patients (132 operated levels) were included. Four patients belonged to Group A and 12 to Group B. Group A exhibited only MEP alerts and showed higher prevalence of peripheral vascular disorders, C3-C4 surgeries, and poorer motor scores in the most affected muscle group; the latter independently predicted alerts with 100% sensitivity at an mMRC threshold of 4. Group B was characterized by only MEP and EMG alerts, significantly longer symptom duration, and myelomalacia spanning two to three levels. Both factors independently predicted intraoperative alerts and were protective when symptom duration was less than 37 months and myelomalacia involved less than two levels. No SSEP alerts occurred.

CONCLUSION

These findings support the use of mIONM during positioning and surgical decompression in anterior cervical procedures for patients with cervical myelomalacia, especially in those with segmental motor deficits, prolonged symptoms, and multilevel myelomalacia.