Discography - Procedure, Benefits, and Limitations

Introduction

Discography is a diagnostic, interventional procedure to confirm or disprove the theory that a specific lumbar disk is the primary source of a patient's lower back pain. It is typically considered when conservative treatments have failed to alleviate severe low back pain, and clinical assessment indicates the pain originates from the intervertebral disk after ruling out other potential sources. The utilization of discography remains a topic of debate in the medical community. Variability and subjectivity in techniques and diagnostic criteria have raised concerns about reliability. However, when standardized diagnostic criteria are employed, the specificity of discography significantly improves.

Recent studies have investigated its long-term effects, revealing a potential increase in disk degeneration and herniation as observed on magnetic resonance imaging. Although the clinical implications are uncertain, it is crucial to consider these risks before conducting discography, possibly necessitating changes in technique. Nonetheless, discography remains the sole method to ascertain whether a patient's low back pain originates from the intervertebral disk, provided careful patient selection, adherence to standardized techniques and criteria, and awareness of potential long-term consequences are ensured.

What Is Discography?

• A discogram, also known as discography, is a diagnostic imaging test used to determine if a particular intervertebral disk is causing back pain.

• Intervertebral disks serve as cushion-like structures between the spine's vertebrae, acting as shock absorbers and providing flexibility. Each disk consists of a sturdy outer layer called the annulus and a soft, rubber-like center called the nucleus. When disks bulge or rupture, they can compress spinal nerves, leading to pain or weakness.

• Contrast liquid is injected into one or multiple spinal disks with X-ray guidance during a discogram. This injection may temporarily replicate the patient's back pain symptoms. Additionally, X-rays or CT (computerized tomography) scans may be performed to visualize the injected disk as part of the procedure.

How Does Discography Work?

• Like light or radio waves, X-rays are a form of radiation that can traverse most objects, including the body. The technician precisely directs the X-ray beam toward the targeted area. The machine releases a short burst of radiation penetrating the body, creating an image on photographic film or a specialized detector.

• Different body tissues absorb X-rays to varying degrees. Dense bone absorbs a significant portion of the radiation, whereas soft tissues (such as muscle, fat, and organs) permit a greater passage of X-rays. Consequently, bones appear white on the X-ray, soft tissue is depicted in varying shades of gray, while air appears black.

• The majority of X-ray images are stored as electronic digital files. This allows the doctor to conveniently access and utilize these stored images for diagnosing and managing your condition.

• Fluoroscopy employs a continuous or pulsed X-ray beam to generate images projected onto a video monitor. Contrast material may be utilized during the examination to delineate the area of interest. Fluoroscopy enables the doctor to observe joints or internal organs in motion. Additionally, the examination captures still images or videos, which are electronically stored on a computer.

How Is Discography Performed?

The discography procedure involves several steps. Firstly, an outpatient setting is chosen for the examination. An intravenous (IV) line is inserted to administer sedation. The patient lies on their side on an examination table, and the area where the procedure will be performed is numbed with a local anesthetic. Guided by real-time X-ray images, a needle is carefully inserted into the center of the disk, and contrast material is injected. The patient may be asked to describe any pain they experience throughout the procedure. Once the injection is complete, pressure is applied to stop bleeding, and a bandage is applied. The IV or intravenous line is then removed. Additional imaging, such as an X-ray or CT scan, may be performed following the injections to evaluate the injected disk(s) further. Afterward, the patient is monitored for 30 to 60 minutes before discharge. Overall, the procedure typically takes about an hour to complete.

What Are the Benefits and Risks Associated With Discography?

Benefits:

• Discography helps determine if a specific intervertebral disk contributes to back pain symptoms.

• X-rays used in the procedure do not leave any radiation in the body.

• Generally, X-rays have minimal side effects within the diagnostic range.

• CT scan is painless, noninvasive, and provides accurate imaging.

• CT scans can simultaneously visualize bone, soft tissue, and blood vessels.

• CT scans detailed images of various tissues, including lungs, bones, and blood vessels.

Risks:

• Any skin-penetrating procedure carries a risk of infection, although it is rare.

• There is a slight risk of allergic reaction to contrast material injection.

• Excessive radiation exposure carries a slight risk of cancer, but the diagnostic benefits usually outweigh this risk.

• Pregnant women should notify their physician and the X-ray technician about pregnancy due to potential risks to the fetus.

• Radiation dosage varies, and caution should be exercised, especially in vulnerable populations.

• CT scans are typically not advised for pregnant women unless medically essential.

• Breastfeeding mothers should postpone breastfeeding for 24 hours following contrast material injection.

• Allergic reactions to contrast materials containing iodine are extremely rare and can be managed by radiology departments.

• While discography is generally safe, potential complications include infection, temporary worsening of back pain, headache, nausea, injury to blood vessels or nerves, bleeding, temporary numbness or weakness, nerve damage, and paralysis.

What Are the Limitations of Discography?

• Discography is generally not the first choice for evaluating back pain due to its invasive nature. It is typically recommended after initial conservative treatments, such as medication or physical therapy, have been ineffective over four to six months. Additionally, since a damaged disk may not always cause pain, discogram results are often interpreted alongside other test findings to formulate a treatment plan.

• In certain cases, MRI (magnetic resonance imaging) or CT scan may be preferred over discography for diagnosing back pain.

• In most instances, plain radiographs, spine MRI, or spine CT (if MRI is not feasible) are the primary diagnostic tests for lower back pain evaluation. Other procedures like myelography or discography occasionally address specific clinical concerns before considering surgical interventions.

Conclusion:

Discography is a valuable diagnostic tool in determining the source of back pain when other methods have been inconclusive. With careful interpretation and integration of its results with other diagnostic findings, discography contributes to a comprehensive understanding of the underlying condition, guiding appropriate treatment strategies for patients seeking relief from back pain.