P130. Intraoperative neuromonitoring findings are predictive of neurological outcomes after decompression for cervical spondylotic myelopathy

Abstract

BACKGROUND CONTEXT Intraoperative Neuromonitoring (IONM) is frequently used by spine surgeons to predict emerging neurological insult and to provide functional feedback prior to development of irreversible neural injury. Despite its widespread use, however, it remains unclear whether various IONM changes are predictive of neurological outcomes in patients who undergo decompression surgery for cervical spondylosis with myelopathy (CSM). PURPOSE To evaluate the prognosticative ability of IONM changes for neurological outcomes after surgical decompression in patients with CSM. STUDY DESIGN/SETTING Retrospective evaluation of a prospectively enrolled cohort of patients who underwent surgery for CSM at the Ohio State University Wexner Medical Center. PATIENT SAMPLE A total of 39 patients were prospectively enrolled in a CSM trial at our institution and underwent decompression surgery between 2013-17. All patients with available intraoperative somatosensory evoked potential (iSSEP), motor evoked potential (iMEP), and spontaneous electromyography (iEMG) recordings as well as perioperative mJOA scores were included in the study. OUTCOME MEASURES The modified Japanese Orthopaedic Association (mJOA) scale evaluated at 1-year following surgery. METHODS Either univariate ANOVA with post hoc analysis (Student–Newman–Keuls) or t-tests were used to analyze DmJOA in relation to iSSEP, iMEP, and iEMG changes. RESULTS During surgery, iMEPs either improved, remained stable, or decreased in 5, 29 and 5 patients, respectively. iSSEPs improved, remained stable, or decreased in 1, 37 and 1 patient, respectively. Twenty-five patients showed spontaneous iEMG activity, which ultimately resolved in all cases. In patients in whom iMEP decreased, remained stable, or improved, mJOA improved by 1.3, 2.0, and 2.8 points 12 months after surgery, respectively. In contrast to iSSEP (p=0.58), iMEP changes and the presence/absence of iEMG activity during surgery were predictive of DmJOA at 12 months (p=0.02 and 0.007, respectively). CONCLUSIONS Decompressive surgery for CSM is generally associated with positive neurologic outcomes. Our findings suggest that patients in whom iMEPs improve potentially benefit the most, whilst those with iMEP decreases or spontaneous iEMG activity benefit the least. Whether IONM findings can prognosticate the degree of functional recovery after decompressive surgery for CSM will need to be confirmed in larger scale studies. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.