Preoperative factors that predict fair outcomes following surgery in patients with proximal cervical spondylotic amyotrophy. A retrospective study

Study design Observational cohort study Objectives To investigate preoperative factors that predict fair outcomes following surgery in patients with proximal cervical spondylotic amyotrophy (CSA) using electrophysiological and neurological findings. Setting Yamaguchi University Methods 54 patients with proximal CSA who underwent surgical treatment of the cervical spine were enrolled. Erb-point stimulated compound muscle action potentials (CMAP) were recorded from the deltoid and biceps brachii muscles. We computed the ratio of affected to normal side CMAP amplitudes in two muscles (deltoid and biceps brachii) and regarded the mean ratio (CMAP-R) as representing the severity of neural involvement. Pre- and postoperative strengths of the most atrophic muscles were evaluated using manual muscle testing. Improvements in strength were classified as excellent (5 grades recovered), good (more than one grade recovered), fair (no improvement), or poor (worsened). Results Surgical outcomes were excellent in 26 patients, good in five, fair in 16, poor in seven. Patients with fair outcomes had lower CMAP-R than those patients with excellent and good outcomes [ P = 0.0099, odds ratio = 0.89 (95% confidence interval, 0.81−0.97; for a change of 10%)]. Eight patients (15%) had a C5 palsy. Conclusions CMAP-R could be used as a reliable predictive factor related to a fair surgical outcome. We must pay attention to the incidence of C5 palsy after surgery.