What is Discography?
Discography is a diagnostic test used to better assess if a patient’s back pain main may be attributed to their intervertebral disks. Studies have shown the prevalence of discogenic back pain being as high as 40%, its prevalence is variable with specific age populations (most notably tends to be higher in younger patients). Discography is a provocative test in which radiographic contrast is injected into the disk (nucleus pulposus) and the spread of contrast as well as the presence or absence of typical discogenic pain is noted during the injection. This is a subjective test that provides greater diagnostic yield to what may be cause of a patient’s back pain.
How does Discography work?
No radiological study alone can definitively ascertain the disc as the primary pain generator. Discography is used to better identify the source of pain in a patient with chronic low back pain without radicular pain (pain radiating down a limb) or MRI documented neural compression. With the increase in pressure from injecting radiographic contrast into a limited space (the nucleus pulposus) pain may be elicited if there is a degenerated disk, radial tear or extrusion of the disk. The outer 1/3 of the disc consist of annular fibers which have nerve fibers that can transmit signals of pain as opposed the inner 2/3 of the disc, the nucleus pulposus which has no nerve fibers. Thus, if there is annular fiber deterioration and contrast is noted to leak from the nucleus pulposus into the outer innervated disc margin this may be a source of pain.
What are the indications for discography?
Provocative discography is often used in conjunction with image findings to provide greater diagnostic yield in better determining the source of patient’s spinal pain. Discography is a tool that can be used to better assess the cause of a patient’s isolated axial back pain. Often indeterminate or equivocal findings may be noted on imaging that do not provide conclusive evidence of a patient’s pain. Discography is a common procedure of request among neurosurgeons and orthopedic spine physicians when deciding if a patient needs a spinal fusion or artificial disc replacement at the disc level. Discography can also be used to provide intradiscal therapy to the patient as emerging therapies such as stem cell, PRP have been discussed as a means to repair the internal disc degeneration.
How do I prepare for discography?
Discography is a surgical procedure that is typically performed in the physician’s office suite or an ambulatory surgery center. Nothing to eat or drink after midnight the day prior to your procedure if you choose to get light sedation. If you are on blood pressure medications, you may take your AM dose with a small sip of water, otherwise hold off on taking your other medications. Consult with your physician at Capitol Pain about blood thinners as these will have to be held prior to the procedure as per safety guidelines.
What should I expect during discography?
Lumbar discography can be a rather uncomfortable procedure as the goal of the procedure is to elicit pain that the patient normally experiences in their back. Intravenous sedation can help to facilitate the procedure; however, caution must be used to avoid over-sedation which could impede communication with the patient.
After being prepped the patient is placed on the exam table belly down. Often a pillow is placed under the lower abdomen in an effort to reduce the normal curvature of the spine and provide better view of the disc. The skin is then prepped via sterile technique with antiseptic solution and drapes are placed.
With use of fluoroscopy the patient and c-arm is positioned to provide optimal entry point of the disc. The skin overlying the disc space is then anesthetized with local anesthetic. A spinal needle is then placed through the skin and advanced until it is seated in soft tissues. As the needle is advanced its trajectory is checked in small increments via the fluoroscopy. Once the spinal needle is introduced into the disc there is a notable increase in resistance noted with further advancement. At this point the physician will use check multiple views of the fluoroscopy c-arm to make sure the needle is appropriately placed in the optimal position central to the disk. Once confirmation is made with the appropriate position provocative testing is conducted.
Often multiple levels which be tested to discern which disc is the cause of the patient’s pain. Thus, all the needles are placed before testing is commenced. Testing involves injecting a small volume of radiographic contrast (often combined with antibiotic) into the discs. The contrast material is injected under live fluoroscopy to observe the pattern of contrast and its spread within the disc. As the material is injected the physician questions the patient about the presence or absence of pain felt with the injection. Severity of the pain, quality of pain, as well the amount of volume injected to induce pain are noted by the physician as is the contrast spread.
A concordant discogram result occurs when the pain elicited from the injection at the pathological disc is noted to be of the typical pain otherwise felt and no pain is felt on injection at the other adjacent disc levels that are otherwise normal in appearance. After injection of all levels final imaging is taken of all disc levels injected and patterns of contrast spread are noted. Often after the procedure patients are sent for CAT (computed tomography) scan imaging to further assess the patterns of disc disruption while the contrast is still present.
What is the recovery time after discography?
Most patients will experience a marked exacerbation of their typical back pain in the days following discography. You may have soreness from the needle punctures that lasts a few days. You may use acetaminophen, ibuprofen or apply an ice pack following the procedure to help reduce any further pain after the procedure.
Can I have sedation for discography?
Since discography is noted to be one of the more invasive pain procedures light sedation may be recommended to provide more comfort to the patient. Patients who are receiving sedation must have a responsible adult with them to drive them home. Once the procedure is complete vitals will be checked frequently over the next 15 to 20 minutes. Once your vital signs are stable, you will be able to go home. Most patients prefer to have a family member or friend drive them for their procedure, however, you may drive yourself to the procedure as long as you are not requesting sedation.
What are the risks for discography?
Commonly incision site bruising may be noted. Less commonly, injury to the exiting spinal nerve can occur. Infection is also a potential risk but is generally quite low as this can be minimized by providing prophylactic antibiotics prior to the procedure and using sterile technique. Discitis or infection within the disk space is the most feared complication with an incidence of less than 1 in a thousand, treatment of discitis involves long term use of antibiotics and removal of the infection source. Often antibiotics can be injected along with the radiographic contrast to further minimize the chance of discitis.