Abstract
Introduction
Significant variability in neurologic outcomes following surgical correction for ASD has been reported. Risk factors for decline in neurologic motor outcomes are poorly understood. The objective of this prospective, multicenter, international cohort study in 15 sites is to evaluate the incidence and risk factors for postoperative neurological motor decline in patients undergoing surgery for complex adult spinal deformity (ASD).
Material and Methods
From September 2011 to October 2012, 273 consecutive patients were prospectively enrolled. One patient lacked baseline ASIA lower extremity motor score (LEMS), and one patient did not have follow-up LEMS leaving 271 (99.27%) subjects for analysis. Decline in neurologic motor outcomes was defined as deterioration in any of discharge or 6 weeks American Spinal Injury Association (ASIA) Lower Extremity Motor Scores (LEMS) compared with pre-operative status. To identify risk factors associated with decline in LEMS, two step statistical analysis was performed. First, 128 candidate variables consisting of demographics, comorbidities, treatment history, disease severity, radiologic parameters and surgical details were screened in bi-variate models. Then, 53 variables that had a p-value of 0.2 or less were included in a multivariate logistic stepwise model.
Results
70 (25.93%) patients showed decline and 200 (74.07%) had no decline in LEMS. Of those with a decline, nine patients (overall rate of 3.33%) had a severe deterioration of > 10 points on LEMS scale. Key factors associated with postoperative neurological deterioration included older age, non East Asian ethnicity, cardiovascular disease, preoperative motor weakness, kyphosis on T12 – S1, focal severe deformity angle, pedicle subtraction osteotomy, thoracic level fusion and intraoperative motor evoked potential change.
Conclusion
Although complex ASD surgery can enhance the quality of life of adult patients with severe deformity, a significant portion of patients with ASD experience a postoperative decline in LEMS. The risk factors identified in this study are useful to help clinicians to anticipate and potentially develop strategies to reduce the risk of postoperative neurologic complications.