Prospective cohort study of mild cervical spondylotic myelopathy without surgical treatment

Abstract

Object Because the main pathology of cervical spondylotic myelopathy (CSM) is spinal cord damage due to compression, surgical treatment is usually recommended to improve patient symptoms and prevent exacerbation. However, lack of clarity of prognosis in cases that present with insignificant symptoms, particularly those of mild CSM, lead one to question the veracity of this course of action. The purpose of this study was to elucidate the prognosis of mild CSM without surgical intervention by evaluation of clinical symptoms and MR imaging findings. Methods Sixty cases of mild CSM (42 males and 18 females, average age 57.2 years) presenting with scores of 13 or higher on the Japanese Orthopaedic Association (JOA) scale were treated initially by in-bed Good Samaritan cervical traction without surgery. These patients were enrolled between 1995 and 2003 and followed up periodically until the date of myelopathy deterioration or until the end of March 2009. The deterioration of myelopathy was defined as a decline in JOA score to less than 13 with a decrease of at least 2 points. As a prognostic factor, the authors used their classification of spinal cord shapes at their lateral sides on axial T1-weighted MR imaging. “Ovoid deformity” was classified as a situation in which both sides were round and convex, and “angular-edged deformity” where one or both sides exhibited an acute-angled lateral corner. The duration of follow-up was assessed as the tolerance rate of mild CSM using Kaplan-Meier survival analysis and compared between 2 groups classified by MR imaging findings. Furthermore, differences between groups were analyzed by various applications of the log-rank test. Results Of the initial 60 cases, follow-up records existed for 55, giving a follow-up rate of 91.7% (38 males and 17 females, average age 56.1 years). The mean JOA score at end point was 14.1, which was not statistically different from the mean of 14.5 at the initial visit. Deterioration in myelopathy was observed in 14 (25.5%) of 55 cases, whereas 41 (74.5%) of 55 cases maintained mild extent myelopathy without deterioration through the follow-up period (mean 94.3 months). The total tolerance rate of mild CSM was 70%. However, there was a significant difference in the tolerance rate between the cases with angular-edged deformity (58%) and cases with ovoid deformity (95%; p = 0.049). Conclusions The tolerance rate of mild CSM was 70% in this study, which proved that the prognosis of mild CSM without surgical treatment was relatively good. However, the tolerance rate of the cases with angular-edged deformity was 58%. Therefore, surgical treatment should be considered when mild CSM cases show angular-edged deformity on axial MR imaging, even if patients lack significant symptoms.