T98. Usefulness of combined somatosensory and motor evoked potentials and electromyography monitoring in intramedullary spinal cord tumor surgeries

Introduction In the surgery of intramedullary spinal cord tumors (IMSCTs), risk of critical injury to motor and sensory pathways is higher due to direct tract manipulation. EMG provides immediate results without averaging during critical phases of the procedure. In this study, we evaluated whether combined use of EMG with SEP/MEP monitoring had any advantages over SEP/MEP monitoring. Methods The authors rewiewed clinical and neurophysiological data of the 25 operations in 21 patients with IMSCT. In these 21 patients, 12 were men and 9 were women; their median age was 41.05 years (range 26–83 years). We monitored SSEP, MEP and continuous free-running EMG during the surgery. Results Combined SEP/MEP/EMG monitoring was successfully performed in 14 of 25 operations. Combined SEP/MEP monitoring was done in 11 operations. New postoperative neurological deficits occurred in 15 operations: 5 had combined sensory and motor deficits, 9 had new sensory deficits, 1 had increased motor weakness. When we analyzed the accuracies, combined SEP/MEP monitoring had a sensitivity of 67%, a specificity of 60%, a positive predictive value (PPV) of 67%, and a negative predictive value (NPV) of 40%. Combined EMG/SEP/MEP monitoring had a sensitivity of 89%, a PPV of 62%. Conclusion Combined SEP/MEP/ EMG monitoring provided higher sensitivity than Combined SEP/MEP monitoring techniques in IMSCT surgery. Combined monitoring with SSEP/MEP and EMG can be more helpful for predicting neurological deficit in this surgery.