Lumbar discography: an update.

Discogenic pain most commonly affects the low back, buttocks, and hips and is thought to be a byproduct of internal disk degeneration. It is postulated that progressive annular breakdown and tearing results in biomechanical and/or biochemical stimulation of the pain fibers that reside in the outer one third of the annulus. Although multiple imaging modalities, most notably MRI, can show morphologic abnormalities of the spine, discography remains the only test that provides physiologic information regarding what role a given intervertebral disk plays in a patient's symptom complex. The controversy surrounding discography is here to stay until more definitive, well-designed studies are performed. In the meantime, there are certain things that can help the discographer maximize the accuracy of the test: 1. Always try to inject one "normal" disk as a "control level." 2. Be alert for factors that are associated with an increased false-positive rate (abnormal non-anatomic pain maps, a history of chronic pain of spinal or nonspinal origin, abnormal psychometric testing, and prior surgery at the injected disk level). In these cases, special attention should be directed to both the patient's verbal and nonverbal cues during disk injection. 3. Do not give any audible clues as to what level is being injected or when the injection is starting or finishing. In this regard, we find it very helpful to have one of our personnel talk with the patient during this portion of the procedure while closely observing the patient for any nonverbal cues regarding their pain response. This distraction is preferable to a silent room where the patient is intensely focused on what is going on with the injections. We also find that music playing during the procedure helps to relax and often distract the patient as well. 4. If the results are equivocal at a level (i.e., you are unable to determine whether or not the patient's pain response was truly concordant), go on to inject another disk level and then come back to reinject more contrast into the disk in question. As radiologists, we tend to focus on the technical aspects of a procedure and the anatomic/morphologic information it provides. However, it cannot be emphasized enough that when performing lumbar discography, the assessment of the patient's pain response during the injection is the most important component of the procedure, and requires not only technical skills, but an understanding of how best to avoid some of the pitfalls that can lead to inaccurate results.