[Relationship of dynamic cord impingement with disease severity and prognosis in cervical spondylotic myelopathy]

To investigate the relationship of dynamic cord impingement of sagittal diameter on flexion-extension cervical magnetic resonance (MR) imaging with disease severity and prognosis in cervical spondylotic myelopathy.A total of 53 patients with cervical degenerative disease were evaluated with regards to the dynamic cord changes of sagittal diameter at neutral and flexion-extension 1.5 T MR imaging from February 2006 to November 2008. The mean follow-up period was 14.6 (11 - 36) months. The factors of age, sex, duration of disease, cervical range of motion and cord signal intensity were considered. The patients were divided into two groups according to the extent of dynamic cord changes of sagittal diameter on MRI (groups of high and low dynamic cord changes). Statistical analyses were performed with SPSS 13.0.The preoperative JOA scores were 9.17 +/- 2.45 and 13.76 +/- 2.81 respectively with a recovery rate of 57.02% +/- 16.23% at the final follow-up. There was no significant difference between the two groups in terms of recovery rate and age. The cervical range of motion and cord signal intensity in group of high dynamic cord changes were higher than those in group of low dynamic cord changes. The preoperative JOA score and duration of disease were lower than those in group of low dynamic cord changes. According to linear regression test between the recovery rate, the preoperative JOA score and the extent of dynamic cord changes, the correlation coefficient were 0.07 (P = 0.643) and -0.27 (P = 0.04) respectively.With the precondition of a short disease duration in cervical spondylotic myelopathy, the extent of dynamic cord changes is correlated with disease severity but shows no relationship with prognosis.