A subclinical impairment of ventilatory function in cervical spondylotic myelopathy.

Abstract

To evaluate the ventilatory function in patients with cervical spondylotic myelopathy (CSM). Prospective cohort study. Medical school in Japan. Thirty-seven consecutive patients with CSM. All the patients had surgical intervention for mild to moderate spastic limb paresis. Analysis of the maximum voluntary ventilation (MVV) in addition to routine spirometry before and after surgical decompression. Functional assessment was made by using the Japanese Orthopaedic Association (JOA) Scale. The MVV (% predicted) increased significantly (P<.002) from 77%+/-19% preoperatively to 84%+/-20% postoperatively. None of the other routine spirometric data (ie, vital capacity, forced vital capacity, forced expired volume in 1 second, peak expiratory flow rate) increased significantly. According to the JOA score, tetraparesis improved significantly (P<.0001) from 8.3+/-3.2 preoperatively to 11.4+/-3.0 postoperatively. The ratio of postoperative to preoperative MVV showed a significant correlation (r=.538, P<.002) with that of the JOA score. MVV provides a useful measure for monitoring ventilatory impairment in patients with myelopathy.