Asymptomatic versus symptomatic herniated thoracic discs: their frequency and characteristics as detected by computed tomography after myelography.

We retrospectively reviewed the myelograms of 433 patients and identified those who had no symptoms or signs referable to the thoracic cord, roots, or nerves. By post-myelography computed tomographic scan criteria, our frequency of asymptomatic thoracic herniated discs (ATHDs) was calculated. Post-myelography computed tomographic scans of 68 ATHDs were analyzed. Their imaging characteristics were compared with our own series of 5 symptomatic thoracic herniated discs and symptomatic thoracic herniated discs in the literature. We were unable to identify any imaging features that could reliably classify a disc as an ATHD or a symptomatic thoracic herniated disc. Our results call into question the propriety of prophylactic surgery for ATHDs, even when the lesions are radiographically impressive.