Appropriate timing of surgical intervention for the proximal type of cervical spondylotic amyotrophy

Purpose The purposes of this study were to evaluate the clinical outcome after surgical treatment of patients with the proximal type of cervical spondylotic amyotrophy (CSA) and to explore the appropriate timing for surgical intervention. Materials and methods A retrospective review was performed on a consecutive cohort of 41 patients who underwent surgical treatment for the proximal type of CSA between 1995 and 2011 at the Nagoya Spine Group Hospitals. We collected information regarding age, type of muscle atrophy, preoperative and final manual muscle test, duration of symptoms, high-intensity areas on T2-weighted MRI images, low-intensity areas on T1-weighted MRI images, levels of spinal canal stenosis, the compression lesion site, cervical kyphosis and surgical procedures (laminoplasty, anterior spinal fusion and posterior spinal fusion). Univariate analyses and multivariate logistic regression analysis were performed to identify correlates of a poor outcome. To explore the appropriate timing for performing surgery, we analyzed the data using receiver operating characteristic (ROC) analysis. Results The duration of CSA symptoms was 11.6 months on average. The surgical results were excellent for 25 patients, good for six, fair for nine and poor for one. On multivariate logistic regression analysis, the duration of symptoms was statistically associated with a poor surgical outcome (OR 1.393, p = 0.011). ROC analysis demonstrated that 4.3 months from the onset of CSA symptoms was the appropriate time to undergo surgery. Conclusions Our results indicate that we should recommend surgical intervention to patients with the proximal type of CSA within about 4 months after the onset of symptoms if conservative treatment has not been successful.