Wednesday, September 26, 2018 1:00 PM – 2:00 PM Navigation and Intraoperative Monitoring: 45. Neuromonitoring signal changes in cervical spine surgery: when is it significant?

Abstract

BACKGROUND CONTEXT Modern cervical spine surgeries utilizes intraoperative neuromonitoring (IONM) in the form of motor evoked potential (MEP), somatosensory evoked potential (SSEP) and electromyography (EMG). However, with a sensitivity ranging from 0% to 100% and specificity ranging from 27% to 100%, there is a need to differentiate between true and false positive signal changes to better supplement intraoperative management. PURPOSE To compare the incidence of neurological deficits in sustained, bimodal intraoperative neuromonitoring (MEP and SEP) signal drops to that of unimodal or transient changes in cervical spine surgeries. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE A total of 257 cases of cervical spine surgery with multimodal neuromonitoring in 3 hospitals in Singapore between 2013 and 2017. OUTCOME MEASURES Incidence of neurological deficits in 3 different patterns of neuromonitoring signal changes. Sensitivity and specifity of MEP and SSEP in cervical spine surgeries. METHODS A retrospective review of IONM and clinical records of all cervical spine surgeries in three hospitals between 2013 and 2017. The procedures were performed by fellowship trained spine surgeons and multimodal IONM was used in all cases. Clinical records were evaluated by two clinicians who were not involved in the patients' management. IONM records of MEP and SSEP were reviewed by a trained neurophysiology technologist. Results were grouped into three groups. In Group 0, there were unimodal signal drops that were transient and resolved back to baseline by the end of surgery. In Group 1, there were sustained unimodal signal changes while in Group 2, there were sustained drops in both the MEP and SSEP. RESULTS A total of 257 cases were reviewed and 207 cases were analyzed after exclusions. A total of 52/207 (25.1%) cases had IONM changes. A total of 10/207 (4.3%) of cases were in Group 0, while Group 1 had 35/207 (16.9%) of cases. 7/207 (3.4%) of cases were in Group 2. Group 0 and 1 had no neurological deficits, while in Group 2, 2/7 (28.6%) had neurological deficits. Both MEP and SSEP were 100% sensitive. SSEP had a specificity of 96.6%, while MEP had a lower specificity at 76.6%. CONCLUSIONS Our study shows that by grouping the signal changes into transient or sustained, and unimodal or bimodal, we are able to better predict which signal drops are significant, thereby allowing for improved intraoperative decision making. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.