224. The utility of neuromonitoring in cervical myelopathy patients

Abstract

BACKGROUND CONTEXT Intra-operative neuromonitoring (IONM) was developed and is now used as a method of monitoring and potentially preserving spinal cord function during critical spine procedures. Although there is in theory utility to the use of this technology, particularly for deformity surgery where corrections may be reversed in conjunction with IONM findings, the utility in degenerative cases for cervical spondylotic myelopathy (CSM) where no similar opportunity exists is lacking in practice. In fact, IONM does add cost and time to each surgery and it may just be used for medicolegal reasons by some physicians. PURPOSE To examine the utility, sensitivity and specificity of IONM for patients undergoing surgery for CSM. STUDY DESIGN/SETTING Retrospective review of a consecutive series of CSM patients undergoing surgery in a safety net county hospital system PATIENT SAMPLE A total of 540 CSM surgical patients. OUTCOME MEASURES N/A METHODS Retrospective comparison of IONM findings was made against preoperative to immediate postoperative and perioperative clinical examination findings for a consecutive series of 540 CSM surgeries performed over a 10-year period from 2009-2019 in a safety net hospital system. The senior author (K.R.) kept track of all positive and negative findings. RESULTS There were seven positive IONM findings where loss of motor evoked potentials suggested a major intraoperative neurologic despite none of these patients having any clinical neurological deterioration pre- to postoperatively, neither subjectively when asking the patient nor objectively on physical examination by the spine team. There were no false negative findings and all IONM negatives were true negatives that maintained baseline neurologic function postoperatively (n=533). Thus, the overall sensitivity of detecting a new neurologic deficit was 0% given there were no true positive cases in this series. The specificity for ruling in normal post-operative neurologic function was 98.7%. CONCLUSIONS Though IONM is proposed to offer benefits during spinal surgery, the present series revealed only false positive findings for CSM surgeries. IONM added significant set-up time and additional cost without patient benefit. These data suggest the use of IONM may not be clinically valuable in practice apart from the idea of medicolegal or intraoperative security, but at the price of significant anxiety, not security, for the 1.3% false positive rate. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.