CT myelographic findings in degenerative disorders of the cervical spine: clinical significance.

CT myelographic data in 80 patients with clinical evidence of nerve-root involvement or long tract signs attributed to degenerative disorders of the cervical spine were classed into five diagnostic groups, and their clinical significance was assessed. Unilateral flattening of the cord by a spondylotic mass or bulging disk in a normally wide canal (group 1) was considered nonspecific because nerve-root signs were nearly as often contralateral as unilateral to the radiologic findings, and none of the patients had long tract signs. As a rule, conventional myelography showed only minor root-sleeve deformity. Concentric compression of the cord in a narrow (stenotic) canal (group 2) proved to produce long tract signs only after the cross-sectional area of the cord had been reduced by about 30% to a value of about 60 mm2 or less. In most cases, nerve-root swelling (group 3) coincided with the side of nerve-root symptoms. A 100% correlation was found between the side of disk herniation with occlusion of the corresponding foramen (group 4) and the side of nerve-root symptoms. In 24 patients, cord and nerve roots showed no abnormalities (group 5). If stenosis of the spinal canal, nerve root swelling, and disk herniation are considered specific CT myelographic signs in nerve-root symptomatology, a specific diagnosis could be made in about 40% of the cases.