Myelographic findings in cervical spines without degenerative changes. Special reference to sagittal diameter of the dural sac.

One hundred cervical myelographies in patients without degenerative changes on plain radiographs were evaluated. Pathologic changes were seen in 75 patients, most of them with congenital spinal canal stenosis and dural sac stenosis. Normal values for sagittal diameter of the dural sac from C2 to C6 were established. It was found that a quotient less than 0.9 between the sagittal diameter of the spinal canal and the midsagittal diameter of the vertebral body indicated congenital stenosis. It is concluded that plain radiographs of the cervical spine are unreliable in predicting the diagnostic value of cervical myelography.