Impact of Regional and Focal Cervical Alignment on Myelopathy Severity: Report of 151 Patients

Abstract

Introduction Cervical sagittal alignment (C2–C7 SVA) has been correlated to myelopathy severity but kyphosis as a regional parameter has not been demonstrated to correlate with health-related quality of life (HRQOL) measures. We hypothesized that regional and focal sagittal cervical alignment may also correlate with HRQOLs in patients with cervical spondylotic myelopathy (CSM). Patients and Methods Post hoc analysis of a prospective, multicenter database of patients with CSM. A total of 151 patients met inclusion criteria (47%): symptomatic CSM, age > 18 years, baseline lateral radiographs, modified Japanese Orthopaedic Association (mJOA) and neck disability index (NDI). Average age was 56.3 ± 11.7 years with females making up 43.9% ( n = 69) of the study population. Regional alignment and HRQOLs were analyzed with patients stratified into a high-cSVA group (hiSVA, n = 45, 0.5 SD ≥ mean) or a low cSVA group (loSVA, n = 43, 0.5 SD ≤ mean). Focal alignment (kyphosis and olisthesis between adjacent vertebrae) analysis was also conducted. Results The hiSVA (mean cSVA 39.4 ± 7.4 mm) cohort had a significantly worse mJOA than the loSVA (mean cSVA 11.31 ± 5.3 mm) cohort (mean mJOA 12.5 vs. 13.7, p = 0.037). No significant correlations between C2–C7 lordosis and HRQOLs existed. There were significant correlations with focal alignment and worse clinical assessments: max sagittal slip with mJOA ( R = −0.24, p = 0.002) and Nurick ( R = 0.18, p = 0.024). Level of slip was also significant, with olisthesis at higher levels correlating with worse health status. Number of kyphotic segments also positively correlated with NDI ( R = 0.19, p < 0.001). Conclusion Similar to previous studies, high baseline cSVA correlated with significantly worse mJOA. Interestingly, the mean cSVA of the hiSVA cohort was 39.4 ± 7.4 mm, suggesting that 40 mm may be a potential threshold below which cervical sagittal malalignment should be corrected. Regarding focal alignment, increased olisthesis is correlated with worse mJOA and Nurick grade, especially at higher cervical levels. Even focal abnormalities all along the cervical spine are correlated with worse NDI, demonstrating that while level of olisthesis may matter, the number of vertebrae with a kyphotic relationship may also cause pain and disability.