Computed tomography in assessment of myelographic nerve root compression in the lateral recess.

Thirty patients with myelographic shortening of a single nerve root sheath without indentation of the dural sac were studied by CT. Lateral disc herniation was diagnosed by CT in 18 patients. The myelograms of these patients were considered suspicious of disc herniation in three patients, uncertain in seven, and misinterpreted as lateral recess stenosis due to bony encroachment in eight. CT is more reliable than myelography in assessment of the etiology of nerve root compression in the lateral recess.