Patient, Procedural, and Practice Variables that Impact the Clinical Utility of IONM during Cervical Spine Surgery: A National Database Analysis

SpecialtyCare is an industry leader in data and research, teaming with surgeons in thousands of hospitals nationwide. We’ve also developed the SpecialtyCare Operative Procedural Database (SCOPE), the largest multi-institutional clinical database, to identify trends and make surgery safer. Our commitment to data and research helps us set benchmarks and lead the industry in OR innovation, allowing us better serve our patients.

SpecialtyCare recently published research that evaluates patient, procedural, and practice variables that impact the clinical utility of IONM during cervical spine surgery.

The Study 

The goal of this study was to facilitate clinical decision making with data from a national database.

IONM Decision Process:

  1. What is the risk of new neurologic dysfunction for a patient having this procedure?
  2. Can that risk of dysfunction be accurately diagnosed by neuromonitoring?
  3. Can actions taken in response to a diagnosis of evolving dysfunction have a therapeutic impact and remediate the risk?



  • Data from 4 separate large-scale retrospective studies (2 published, 2 in submission) of extradural cervical procedures performed in the US
  • Used various statistical analyses and logistic regression models controlling for different variables (diagnosis, age, approach, levels, and more)

Key Take Home Points

  • Baseline risk is dependent on diagnosis
  • Relative Risk Reduction is NOT dependent on diagnosis
  • Risk Elevation is dependent on modality type and anatomic pattern of IONM Alert
  • Risk Reduction is dependent on reversibility/resolution of IONM Alert
  • Diagnostic accuracy is dependent on monitorability of MEPs, which is anesthesia dependent

Take Home: Risk Remediation

  • Baseline Risk is higher in myelopathic patients, but risk is not negligible for radiculopathic patients
  • Risk elevation if there is an alert:
    • Is higher for MEP alerts, and is highest for multimodality MEP & SSEP Alerts
    • Is higher for C5 nerve root or Arm alerts, and is highest for Cord alerts
    • Is relatively independent of diagnosis
  • Risk reduction is there is an alert:
    • Is dependent on resolution of MEPs
    • Is relatively independent of diagnosis

Conclusion: Risk is elevated in procedures with MEP alerts and, in particular, if pattern is diagnostic of C5 nerve root or cord dysfunction. The resolution of MEP alerts is associated with a significant risk reduction.

Take Home: Baselines

  • Inhalational agents significantly decrease the monitorability and amplitude of all muscle MEPs
  • Compared to distal hand/foot MEPs, proximal MEPs are:
    • Less likely to be monitorable
    • Smaller in amplitude
    • Disproportionately negatively impacted by inhalational agents
  • Inhalational agents decrease diagnostic accuracy because:
    • Less likely to have monitorable baseline MEPs
    • Have smaller amplitude MEPs, on average, which may prompt alert criteria shifts, e.g., from a 50-65% amplitude attenuation to complete loss of response

Conclusion: Balanced anesthesia is suboptimal for monitoring neurologic function with MEPs and particularly suboptimal for monitoring nerve root function.

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