Analysis of Intraoperative Neurological Complications in High-Risk Spinal Surgery with the Use of Motor Evoked Potential Monitoring

ABSTRACT

STUDY DESIGN: This is retrospective study. OBJECTIVES: To evaluate the risk of operative techniques using Motor Evoked Potential (MEP) in high-risk spinal surgery. SUMMARY OF LITERATURE REVIEW There are few studies regarding the evaluation of operative techniques by MEP. MATERIALS AND METHODS: We studied 33 cases that had MEP during surgery from July 2007 to March 2009. Diagnoses included post-traumatic kyphosis (PTK) in eight cases, congenital deformity in eight cases, degenerative lumbar deformity in eight cases, ankylosing spondylitis (AS) in three cases, spinal tumor in three cases, adjacent segmental disease in two cases, and post-surgical kyphosis in one case. Posterior vertebral column resection (PVCR) and pedicle subtraction osteotomy (PSO) were performed in 27 cases (81.8%) and, in the others, posterior decompression with discectomy was performed. We analyzed the risk of operative techniques and evaluated the MEP. RESULTS: MEP showed abnormal signal change in five cases (PVCR one case, compression and distraction four cases). The AS case did not demonstrate neurological change after surgery. Though the PTK on T12 operated by PVCR case did not show an abnormal MEP result, neurological change was observed postoperatively. The sensitivity, specificity, percent of false negatives, and percent of false positives of MEP were 80.0%, 96.4%, 20.0%, and 3.6%, respectively. CONCLUSIONS: MEP monitoring is a useful method to detect neurological injury during high-risk spinal surgery with satisfactory specificity. For low sensitivity and a high false negative rate, increased monitoring of cases and continuous follow-up is needed. In conclusion, compression and distraction and PVCR are high-risk techniques in kyphotic deformity correction.