High resolution computed tomography in the diagnosis of laterally herniated lumbar discs.

Fourteen patients presenting with lumbar radiculopathy had normal or nondiagnostic plain radiographs, myelograms and polytomes of lumbar spine. The high resolution computed axial tomography (HR CAT) demonstrated laterally herniated discs in all cases. The CAT findings correlated well with the clinical presentations and were proven at surgery to be the cause of lumbar nerve entrapment. The preoperative accurate localization of the lesion resulted in complete postoperative relief of lumbar radiculopathy and back pain in 12 cases with two cases, though relieved of the radiculopathy, had residual mild nondisabling low back pain. In cases presenting with sciatica and having nondiagnostic myelograms and other conventional radiological studies, HR CAT of spine is the only reliable radiological test that can be used to rule out laterally herniated lumbar discs.