Abstract
The authors studied the relevancy of unstable degenerative spondylolisthesis to cervical spondylotic myelopathy (CSM) in elderly patients. Of the 68 patients, all over 65 years old, surgically treated for CSM during the past 10 years, 26 vertebrae of 23 patients showed a horizontal displacement of the vertebra of 3.5mm or more, estimated by flexion/extension radiography before surgery. Twenty-one patients had less than 2mm or no horizontal displacement. The displacements occurred at the C3 on C4 and C4 on C5 levels in 12 each. C3 tended to displace posteriorly, and C4 anteriorly. In these patients, the entire range of motion (52.2±3.2°) of the cervical spine with cervical spondylolisthesis was significantly greater than those (40.9±4.0°) without cervical spondylolisthesis. Further, 20 of 26 displacements were responsible for CSM as evidenced by both MRI before surgery and spinal cord evoked potential studies during surgery.
The current study's findings suggest that there is a higher incidence of degenerative spondylolisthesis of the cervical spine in elderly CSM patients than has been previously described. The spondylolisthesis, if associated with a relatively greater mobility, results in spinal cord compromise at the upper cervical levels.
