C5 Palsy of Patients with Proximal-Type Cervical Spondylotic Amyotrophy

STUDY DESIGN: An observational cohort study design was adopted in this study. PURPOSE: This study was designed to investigate preoperative factors that predict poor outcomes following surgery in patients with proximal-type cervical spondylotic amyotrophy (PCSA) using radiological findings. OVERVIEW OF LITERATURE: We evaluated the preoperative factors associated with poor outcomes using electrophysiological and neurological findings. However, the preoperative factors associated with poor outcomes remained unclear. METHODS: Sixty patients with PCSA who underwent surgical treatment of the cervical spine were enrolled. The radiological findings on plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) were evaluated. The cervical lordotic angles, C2–C7 sagittal vertical axis (SVA), and T1 slope were assessed on a lateral radiograph in the neutral position. CT was used to assess the width of the intervertebral foramen and the anterior protrusion of the superior articular process on the axial view. MRI was used to determine the number of levels of compression (NLC) and the presence of a high-intensity area in the spinal cord in the T2-weighted midsagittal view. The preoperative and postoperative strengths of the most atrophic muscles were evaluated using manual muscle testing. Improvements in strength were classified as excellent (five grades recovered), good (more than one grade recovered), fair (no improvement), or poor (worsened). RESULTS: The prevalence of C5 palsy was 17% (10/60). Patients with poor outcomes had higher NLC and Δ C2–C7 SVA than patients with excellent, good, and fair outcomes (p=0.015; odds ratio [OR], 5.758; 95% confidence interval [CI], 1.397–23.726 for a change of 10% and p=0.048; OR, 1.068; 95% CI, 0.992–1.141 for a change of 10%, respectively). CONCLUSIONS: ΔC2–C7 SVA and NLC may be used as prognostic factors for achieving a poor outcome following surgery in patients with PCSA. More focus is needed on preventing the increase in ΔC2–C7 SVA.