Lumbar Discography for Back Pain Diagnosis

A lumbar discogram, also called lumbar discography, is a minimally invasive, presurgical diagnostic test devised to determine if an intervertebral disc in the lower spine is the primary cause of back pain with or without leg pain (sciatica).1

In a discogram test, a contrast agent is injected into the disc that is suspected to be the source of pain. The injection increases pressure within the disc and stimulates symptoms.

  • The test involves injecting a contrast agent into the disc that is suspected to be the source of pain. The injection increases pressure within the disc and stimulates symptoms.1
  • The contrast agent reveals high-contrast anatomical information about the disc, such as the integrity of its structure, possible tears, and potential degenerative changes, through a series of x-rays or computed tomography (CT) scans.1

The results of a discography test influence the surgical decision-making process and accurate selection of spinal levels for a lumbar spinal fusion surgery.1 The test can also be performed in the neck (cervical discography) or upper back (thoracic discography) to analyze disc-related pain in those spinal segments.

Discography is typically not used as a stand-alone test to diagnose a diseased disc. It is used in conjunction with a specialized, sensitive imaging test, such as CT or magnetic resonance imaging (MRI) scan.

This article is a guide to the lumbar discogram test, including its key uses, mechanism of action, influence on surgical outcome, procedural details, and potential risks.

advertisement

When Lumbar Discogram Is Considered

A discogram may be recommended after several attempts of nonsurgical care have failed to provide relief from sciatica or back pain and before surgery is considered.1 The test may be used to:

  • Evaluate back pain or sciatica when non-invasive imaging, such as MRI, does not indicate clear structural abnormalities1,2
  • Correlate the abnormality of a disc with the symptoms and signs, such as back pain, leg pain and numbness, leg weakness, calf and/or foot pain, etc1
  • Investigate persistent, severe symptoms that do not correlate with equivocal or inconsistent MRI or CT results1
  • Identify painful spinal levels accurately, when MRI and/or CT findings show disc disease at multiple levels1

Less commonly, a lumbar discogram may be used to assess back pain and sciatica from failed back surgery syndrome or differentiate recurrent disc herniation from a painful pseudoarthrosis (failure of adequate fusion after a spinal fusion surgery) of the spine.

When Lumbar Discogram May Not Be Performed

The presence of specific conditions or factors may not be favorable in performing a discography due to potential harm to the patient or failure to achieve the desired results.1 These conditions or factors include but are not limited to:

  • The existence of a known bleeding disorder and the related use of anticoagulation therapy1
  • A general infection in the body or localized skin infection on the lower back1
  • An allergy to the contrast agent injectate1
  • A disc that has been surgically treated1
  • A solid bone fusion that does not allow access to the disc1
  • Severe spinal cord compromise at the disc level to be investigated1

As with most minimally invasive diagnostic tests, a lumbar discography is usually not performed in women with a suspected or confirmed pregnancy.1

How Lumbar Discography Works

A discography is designed to provoke the suspected diseased disc to reproduce painful symptoms and signs that the patient typically feels. If the provoked symptoms are similar to the patient’s everyday pain, the test is considered positive.3

A discogram includes disc puncture and pressurization.3 A contrast agent is injected into the innermost core (nucleus pulposus) of the suspected disc and the resistance encountered during this injection is noted.1

  • A normal lumbar disc usually takes up to 1.5 mL of contrast agent and a degenerated lumbar disc typically absorbs a volume of more than 2 mL.1 Analyzing the amount of injectate absorbed by the disc may help the physician understand the disc’s health and condition.
  • The injection is terminated when a firm resistance is felt or if severe pain is produced.1
  • While the contrast agent is being injected into the disc, x-ray imaging or CT scans are taken sequentially to view the intake, which may travel upward, downward, and/or sideways; or be confined inside the disc.1
  • If the disc is normal, the injectate remains inside the core of the disc and appears like a symmetrical cotton ball or hamburger bun on the x-ray or CT imaging.1
  • In a lumbar degenerated disc or lumbar herniated disc, the contrast agent spreads into the tears along the outer membrane (annulus fibrosus), revealing an asymmetrical image on the x-ray or CT scan. For example, when a single tear is present in the annulus fibrosus, this finding is interpreted as a “candle-drip appearance.”1

The contrast agent spreads into the tears in the annulus fibrosus of the disc, which can be observed by the physician on a CT scan or x-ray imaging.

Pain provocation during a discogram procedure occurs due to the stretching of the fibers within the disc, pressure on the sciatic nerve roots, and a change in pressure inside the disc. If possible, an adjacent normal disc may be injected as a reference or control to provide an indication of the patient's level of pain tolerance and the reliability of the patient's responses at the suspected disc level(s).1

Pain Felt During Discography

Pain response during a discography procedure is typically classified in relation to the patient’s familiar pain symptoms and may include:

  • No pain reproduction1
  • Pain that is different from the usual painful symptoms1
  • Pain that is somewhat similar to the usual painful symptoms1
  • Pain identical to the usual painful symptoms1

These reactions are matched with the appearance of the disc on the x-ray or CT scan. Abnormal discs with concordant pain provocation symptoms are considered a positive discogram.

Influence of Discography Results on the Outcome of Spinal Surgery

There is limited research to support the use of discography and subsequent surgical outcome of the treated disc/spinal segment.

A study that investigated 195 patients with discography and subsequent surgeries revealed:

  • 89% of 137 patients with positive discograms had successful surgical outcomes1,4
  • 52% of 25 patients whose discs showed structural abnormality but had no provocation of symptoms on discography had successful surgical outcomes4

Some research suggests that a positive discogram result coupled with positive MRI findings at the same spinal segment may further improve surgical outcomes compared to relying on discography alone. In a study including 53 patients with pain stemming from the L5-S1 disc, a 75% surgical success rate was seen with both positive discograms and abnormal imaging on MRI scans, compared to a 50% success rate in patients with a combination of positive discograms and normal MRI results.1,5

advertisement

Potential Long-Term Complications of Discography

Discography may be regarded as a controversial procedure by some researchers due to the rare probability of long-term side effects and complications.6

Studies that included long-term follow-ups of individuals who had a discography procedure on one or more lumbar discs revealed:

  • Disc herniation: a likelihood of lumbar disc herniation of the evaluated disc if a pre-existing defect in the annulus (the outer layer), such as a tear, or weakness was present7
  • Disc degeneration: the possibility of lumbar disc degeneration, which may be provoked by the puncture and pressure exerted during the discography procedure8

Research also suggests that the height of the disc and its function may be reduced over time.8

The actual mechanism of pain provocation through disc pressurization is not fully understood.1 Despite these barriers, many medical professionals consider discography a valuable tool in the investigation of disc-related pain unresolved by MRI or CT scans and in patients for whom surgery is contemplated. Due to the possibility of potential complications, this diagnostic tool may not be a method of choice for several patients.

References

  • 1.Peh W. Provocative discography: Current status. Biomed Imaging Interv J. 2005;1(1):e2. DOI:10.2349/biij.1.1.e2 Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3097593/
  • 2.Stretanski MF, Vu L. Fluoroscopy discography assessment, protocols, and interpretation. In: StatPearls. StatPearls Publishing; 2022. Available from: https://pubmed.ncbi.nlm.nih.gov/34283485/
  • 3.Guyer RD, Ohnmeiss DD, Vaccaro A. Lumbar discography. The Spine Journal. 2003;3(3):11-27. doi.org/10.1016/s1529-9430(02)00563-6
  • 4.Colhoun E, McCall I, Williams L, Cassar Pullicino V. Provocation discography as a guide to planning operations on the spine. The Journal of Bone and Joint Surgery British volume. 1988;70-B(2):267-271. doi.org/10.1302/0301-620x.70b2.2964449
  • 5.Gill K, Blumenthal SL. Functional results after anterior lumbar fusion at L5-S1 in patients with normal and abnormal MRI scans. Spine. 1992;17(8):940–2. doi.org/10.1097/00007632-199208000-00012
  • 6.Cuellar JM, Stauff MP, Herzog RJ, Carrino JA, Baker GA, Carragee EJ. Does provocative discography cause clinically important injury to the lumbar intervertebral disc? A 10-year matched cohort study. The Spine Journal. 2016;16(3):273-280. doi.org/10.1016/j.spinee.2015.06.051
  • 7.Poynton AR, Hinman A, Lutz G, Farmer JC. Discography-induced acute lumbar disc herniation: a report of five cases. Journal of Spinal Disorders & Techniques. 2005;18(2):188-192. DOI: 10.1097/01.bsd.0000150278.49549.4e
  • 8.Carragee, Eugene J.; Don, Angus S.; Hurwitz, Eric L.; Cuellar, Jason M.; Carrino, John; Herzog, Richard (2009). 2009 ISSLS Prize Winner: Does Discography Cause Accelerated Progression of Degeneration Changes in the Lumbar Disc. Spine. 34(21), 2338–2345. DOI: 10.1097/brs.0b013e3181ab5432
Pages: