Pain expert Dr. Scott Fishman answers questions about back pain:
Q: What is a discogram?
A: A discogram is a procedure where a needle is placed into a spinal disc in the back. The disc is then injected with contrast material, i.e., dye, that allows the disc to be examined under X-ray. This X-Ray (which is also called "fluoroscopy") is used to guide the procedure. The purpose of the discogram is two-fold: 1) to examine the integrity of the disc - that is, to determine if it is bulging or bursting. A burst disc is what physicians call a "herniated disc." Fluoroscopy may also determine if there are irregularities in the shape of the disc, which will appear under the X-ray as stretch marks - marks that are bulging out from the disc. This is called a "disc bulge." Either a herniation or disc bulge are referred to commonly by the term "slipped disc."
Either of these disc problems can cause pressure on nerves, the spinal cord around the spinal bones and pressure on the disc itself -and each of these can potentially cause pain. But we have found recently that the disc itself can cause pain. Therefore, the second part of the discogram includes injecting enough fluid into the disc so that the disc becomes pressurized.
Once the disc is pressurized, it may reproduce the pain that the patient experiences. If pressurization does induce pain, then this may be suggestive evidence that the disc itself is the source of the pain. Thus, pressurization of the disc helps determine if the pain is from the disc alone, as opposed to from one or many of the other structures in the back that can also cause back pain.
A third part of the discogram may include sending the patient to get a CAT scan of the back directly after the discogram. A CAT scan may provide a higher resolution X-Ray view of how the dye in the disc spreads. This may then help determine where there might be imperfections in the disc, if not frank tears or holes. The CAT scan may outline and define areas of irregularities in the disc surface, as well as areas where the dye has potentially leaked out. A disc that is unable to pressurize during a discogram is possibly ruptured.
If the disc is the source of the pain, there are some potential treatments available to the patient. One of these treatments is called an "IDET" or Intra-Disco-Electrothermal-Annuloplasty - which is a big term for simply threading a thin filament into the disc and applying heat to the inside surface. The heat serves to do many different things, one of which is to reduce pain. However, physicians are not absolutely sure what exactly the mechanism is for reducing disc pain, but we believe it may have to do with melting the pain nerves within the disc, or by helping the disc to restructure itself and become more supportive and sealed.
Back surgery may be another possibility to repair the disc and reduce the pain. Another option is to do nothing and hope the disc heals itself naturally. However, we don't know the long-term consequences of utilizing this notherapy approach for patients with disc problems. In other words, we don't know how many patients will get better on their own, without any medical or surgical intervention. These are important facts that hopefully will be revealed by ongoing scientific research in this area of pain medicine.