Lumbar discography for back pain diagnosis

By: Philip R. Shalen, MD
October 5, 2000

Lumbar discography is an injection technique used to evaluate patients with back pain who have not responded to extensive conservative care regimens. The most common use of discography is for surgical planning prior to a lumbar fusion.

This diagnostic procedure – also called a discogram – is a controversial one.

• The protagonists of discography believe the information gleaned from this examination is unobtainable any other way.

• The procedure’s antagonists feel the responses evoked from disc pressurization are not useful in evaluating back pain patients.

This article does not extol the use of discography; rather it addresses some aspects of the procedure that may make a patient more at ease with what is an uncomfortable exam.

Indications for a discogram

The indications for getting a discogram prior to a lumbar fusion surgery are extremely variable amongst spine surgeons. Ordering the procedure depends on access to a skilled discographer. A discogram is basically a very subjective test, and if there are no experienced discographers available, then the spine surgeon may forego the test since a poorly done discogram does not yield any useful information.

Lumbar discography is considered for patients who, despite extensive conservative treatment, have disabling low back pain, groin pain, hip pain, and/or leg pain. When a variety of spinal diagnostic procedures have failed to elucidate the primary pain generator, these individuals may benefit from lumbar discography especially if spine surgery is contemplated.

Unique aspects of discography

It should be understood that the discogram is less about the anatomy of the disc (what the disc looks like) and more about its physiology (determining if the disc is painful). It is well known to discographers that a really abnormal looking disc may not be painful and a minimally disrupted disc may be associated with severe pain. It is impossible to definitively diagnose a painful disc without performing a discogram.

The Lumbar MRI and CT Myelogram are very sensitive anatomic tests but are not very specific in defining actual pain generators. The lumbar discogram, if performed properly, is designed to induce pain in a sensitive disc. A spinal fusion procedure that is designed to obliterate an internally disrupted, painful disc (pain generator) would not be the procedure of choice if pressurization of the disc didn’t reproduce the patient’s clinical discomfort. The spine surgeon needs to be absolutely sure that the level or levels being fused are responsible for the patient’s pain.

If the fused levels were not initially painful, spine surgery will not help, and the patient will be left with a fused spine and probably still be in pain. Since a spine fusion procedure carries a significant level of risk and healing time, the more information that can be obtained prior to back surgery the better.