Role of SSEP and MEP as a Predictor of Postoperative Outcome in Spine Surgery Cases: A Prospective Observational Study

BACKGROUND: Neurophysiological monitoring is practiced as a diagnostic modality to determine intraoperative neural damage. There remains a dearth of significant research underlining its role in determining a patient's motor or sensory improvement, along with predicting postoperative neurological deficit. OBJECTIVES: To study the intraoperative neurophysiological changes in somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) in spinal surgery cases and their use as determinants of postoperative outcome. MATERIALS AND METHODS: A prospective observational study. Patients undergoing spine surgeries, irrespective of their etiology and procedure, were monitored using MEP and SSEP. Groups were made based on changes in intraoperative neuromonitoring data. Outcome was observed by clinical assessment, in the immediate postoperative phase (after 48 h) and after 6 months. RESULTS: Total of 68 patients were included. Patients who had transient MEP decline had no postoperative deficits. On the contrary, these patients, along with the cases with no MEP change or improved MEP trace from baseline, had improvement from baseline motor examination. Of the nine patients showing a permanent MEP decrease, eight had postoperative motor deficits. Similarly, three patients had intraoperative SSEP decline, of whom 1 had postoperative sensory deficit. In 38 patients, there was improvement in MEP/SSEP from baseline readings intraoperatively, showing neurological improvement too. CONCLUSION: Along with supporting the hypothesis of benefits of intraoperative neurophysiological monitoring at predicting postoperative outcome and preventing clinical deficit, this study also suggests higher sensitivity and specificity of MEP as compared to SSEP in spine surgery cases.