Cervical spondylotic stenosis and myelopathy: evaluation with computed tomographic myelography

To determine which components of cervical spondylosis are most frequently present in patients with myelopathy.

We reviewed the findings in 93 patients who underwent surgical decompression for cervical spondylotic myelopathy between January 1986 and December 1989 at Mayo Clinic Rochester.

All 93 patients (72 men and 21 women) underwent computed tomographic (CT) myelography. In addition, magnetic resonance imaging scans were available in 25 patients, and plain CT scans were obtained in 2.

A review of CT myelograms revealed that all neurocompressive intraspinal spondylotic changes were reflected in the shape of the spinal cord. Among the 93 patients with myelopathy, the configuration of the spinal cord could be categorized into primarily three dominant types: A (severe encroachment that compressed the cord into the shape of a banana; N = 40), B (moderate encroachment that produced less prominent compression; N = 23), and C (moderate bilateral uncovertebral spurs; N = 12). As a comparison group, 30 patients with similar spinal cord deformities but without progressive myelopathy were analyzed. Correlation of the two groups showed that myelopathy was present in up to 98% of patients with type A spinal cord, in 75% with type B, and in 71% with type C. The findings on magnetic resonance imaging were similar to those on CT myelography, but the bony spondylotic components were less readily seen.

The precise pathophysiologic mechanism of myelopathy in spondylosis remains an enigma. Although the bulk of the data on our patients supports direct compression, we believe that the cause is multifactorial.