Epidurography & discography

Epidurography and discography are older radiographic techniques that are not performed very often now that CT and MRI are more readily available and more cost effective. Both techniques are used primarily in the diagnosis of cauda equina disorders, such as L7-S1 intervertebral disc disease and other disorders (e.g., ligamentous hypertrophy). While epidurography is inexpensive and relatively easy to perform, it does not allow transverse imaging and provides little to no information about the nerve roots within, or just beyond, the intervertebral foraminae peripherally.

Epidurography involves injection of a contrast agent, typically iohexol or iopamidol, into the epidural space at L7-S1, the sacrocauadal junction or at intercaudal spaces in the tail to allow evaluation of the cauda equina and peripheral nerves of the tail.

Discography involves injection of a contrast agent, typically iohexol or iopamidol, directly into the nucleus pulposus of a disc, most often the L7-S1 disk, and is best performed with fluoroscopic or CT guidance. It is difficult to inject contrast into normal discs, but 2-3 mL of contrast agent can often be easily injected into a large-breed dog with a degenerative L7-S1 disc.

Epidurogram from a dog with an L7-S1 disc protrusion. Modified and used with permission from: http://www.amc-cove.com/services/lumbosacral.php