Discography: A Review

Discography in practice: a clinical and historical review

Chronic low back pain is the most common cause of disability in individuals between the ages of 45 and 65. Given the variety of anatomic and pathophysiologic causes of persistent low back pain, it is a difficult diagnosis for clinicians to treat. Discography is a diagnostic option that may link a patient's subjective complaints of spinal pain to symptomatic disk disease when non-invasive imaging, such as magnetic resonance imaging (MRI), does not find structural abnormalities. A controversial procedure, discography is only necessary to assess painful discs prior to surgical interventions. For accurate discogram interpretation an experienced spine interventionalist must be careful to exclude false positive results and be aware of the patient's underlying psychological state. This literature review will discuss the following: anatomy and function of the spine and intervertebral disc, intervertebral disc degeneration and discogenic pain, history of discography, indications and contraindications, a description of the procedure, complications, and the current debate regarding its outcomes.

Lumbar discography: current concepts and controversies

Lumbar provocation discography is an invasive diagnostic procedure to identify pain originating from within the lumbar discs. Specific morphological changes within the disc, classified as radial fissures, can be imaged following the injection of radiopaque contrast into the nucleus pulposus. The reproduction of concordant low back and/or referred somatic pain to the lower extremity under controlled conditions and the demonstration of annular radial tears are part of a spectrum of internal disc disruption that is separate from disc degeneration. A review of the validity and technique of lumbar discography as well as recently described causes of false positive responses are presented.

Provocative discography: Current status

Low back pain is a common clinical problem that may be due to a variety of causes, including disc disease. Provocative discography is an imaging-guided procedure in which a contrast agent is injected into the nucleus pulposus of the disc. Despite its controversial history, it remains the only imaging technique that provides both anatomical and functional information about a diseased disc. Disc morphology is usually assessed on either radiographs or computed tomography (CT), or both. Functional evaluation of the disc consists of pain provocation and careful assessment of the patient's response to pain. As provocative discography is an invasive procedure, it should not be used as a screening study in patients with back pain. It should instead be reserved for carefully- selected patients whose painful symptoms cannot be explained by findings on non-invasive imaging modalities such as magnetic resonance imaging or CT, and who are not responsive to conservative measures. Discography is helpful in selection of patients and disc levels to be operated upon. Careful application of indications and meticulous technique are however required if a successful outcome is to be expected.

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.

Does needle insertion site affect diskography results? A retrospective analysis

STUDY DESIGN

A retrospective clinical data analysis was performed.

OBJECTIVES

To determine the effect of needle insertion site on provocative diskography results, and to ascertain whether performing diskography ipsilaterally to a patient's reported pain leads to a higher rate of false-positives.

SUMMARY OF BACKGROUND DATA

In certain groups of patients, provocative diskography is associated with a significant false-positive rate, which can lead to misdiagnosis and inappropriate treatment. Although purported by some to be a cause of false-positive diskogram results, the effect of needle insertion site on diskography results has yet to be determined.

METHODS

The charts of 127 patients who underwent diskography were evaluated to determine the relationship between the location of pain, needle insertion site, and diskography results.

RESULTS

Performing diskography on the side ipsilateral to a patient's pain did not result in a higher incidence of positive diskogram results.

CONCLUSION

False-positive diskography results are unlikely to result from performing the procedure on the same side as a patient's reported pain.