The association between cervical focal kyphosis and myelopathy severity in patients with cervical spondylotic myelopathy before surgery

Abstract

Purpose: Cervical focal kyphosis could often be observed in patients with cervical spondylotic myelopathy (CSM). However, the association between it and myelopathy severity remains unclear. This study aims to elucidate the association between cervical focal kyphosis and myelopathy severity before surgery.

Methods: A retrospective review of 191 consecutive patients treated for CSM from 2017 to 2019 was surveyed. Seven MRI and five radiographic parameters were measured, clinical parameters were included. Patients were divided into two sagittal focal angle groups (lordosis/kyphosis) and two disc herniation severity groups (severe/non-severe). The potential risk factors of myelopathy symptoms were analysed.

Results: Significant correlations between cervical sagittal focal angles, several other imaging findings and myelopathy severity were found in both total patients (R² = 0.51, P < 0.001) and non-severe disc herniation patients (R² = 0.73, P < 0.001) in multivariate regression models. Compression ratio of spinal cord exhibited the strongest correlation with JOA scores (r = - 0.567, P < 0.001). Cervical focal angles on MRI exhibited a stronger negative correlation with JOA scores (r = - 0.429, P < 0.001) than did angles on the other three postures on radiographs. Dramatic differences in JOA scores could be found in patients with non-severe cervical disc herniation, when a subgroup analysis was performed between cervical lordosis group and more than 4° kyphosis group (14.2 ± 1.7 vs. 11.1 ± 1.7, P < 0.001).

Conclusion: Cervical focal kyphosis associates with severe myelopathy symptoms in patients with CSM, especially without severe disc herniation. This association may indicate an optimal cervical focal angle in surgical plan. It appeared feasible to assess both the cervical focal angles and spinal cord compression on supine MRI.

Keywords: Cervical kyphosis; Cervical malalignment; Cervical spondylotic myelopathy; Compression of spinal cord; Increased signal intensity.