The application value of intraoperative neurophysiological monitoring in cervical spinal canal stenosis decompression surgery.

Background Context: Although intraoperative neurophysiological monitoring (IONM) has been widely recognized and used in spine surgery, its characteristics vary for different types of spinal disorders, necessitating the development of tailored monitoring strategies. Cervical spinal stenosis presents complex clinical symptoms and carries significant surgical risks, creating a critical need to clarify the monitoring features, alert patterns, and their relationship with outcomes in such surgeries. A comprehensive assessment and the development of a refined IONM monitoring plan throughout the perioperative period is an important direction for future research.

Purpose: This study aims to investigate the influencing factors of intraoperative neurophysiological monitoring (IONM) alarm events in patients with cervical spinal canal stenosis and to evaluate the predictive value of different IONM alarm patterns on neurological recovery following decompression surgery.

Design: Retrospective study.

Patient Samples: This analysis included 1,622 patients who underwent cervical spinal canal decompression surgery and had complete IONM monitoring data between February 2017 and December 2022.

Outcome Measures: The preoperative and postoperative neurological status of the patients was assessed using the modified Japanese Orthopaedic Association (mJOA) score. The primary IONM alarm indicators included somatosensory evoked potentials (SSEP) and transcranial motor evoked potentials (MEP), compared to the preoperative baseline.

Methods: Logistic regression was employed to analyze the correlation between preoperative diagnostic risk factors and intraoperative alarm events. Additionally, a multifactorial interaction analysis was performed to determine the relationship between IONM changes and the reversibility of alarms with the six-month mJOA recovery rate.

Results: Preoperative diagnoses of the ligamentum flavum hypertrophy and/or ossification of the posterior longitudinal ligament, combined with an mJOA score <12, were identified as high-risk factors for intraoperative alarms. The sensitivity of alarms in the high-risk group was 100%, with a positive predictive value of 90.6%; in the low-risk group, the sensitivity was 91.7%, with a positive predictive value of 40.74%. Variance analysis indicated that the mJOA improvement rate at six months was significantly lower in patients with irreversible IONM alarms compared to those with reversible alarms. Interaction analysis suggested that the reversibility of intraoperative alarm events was a principal predictor of postoperative outcomes, while risk factors for alarms had predictive value only in patients with irreversible alarms.

Conclusions: In patients with cervical spinal canal stenosis caused by disc degeneration, the presence of ligamentum flavum hypertrophy, ossification of the posterior longitudinal ligament, and preoperative mJOA scores <12 are significant high-risk factors for intraoperative alarms. The sensitivity and positive predictive value of intraoperative alarms in the high-risk group were significantly higher than those in the low-risk group. Moreover, patients with irreversible alarms exhibited poorer prognoses compared to those with reversible alarms, and preoperative alarm risk factors should not be considered independent predictors of patient outcomes.