Thoracic discography is done at a lesser rate than cervical or lumbar discography because the thoracic spine is relatively stable and disc problems are much less likely in the thoracic area when compared to the cervical area and the lumbar area. It is a test to look for disc problems in the thoracic part of the spine. There are many more problems with the thoracic spine, such as muscle pain, pain with the spine, visceral pain masking thoracic pain and facet joint pain.
The purpose of having a thoracic discogram is to see if a damaged disc is causing thoracic pain. It is similar to a lumbar and cervical discogram in that it is used to identify specific discs that are pinching on nerves causing pain in the back or in the area a peripheral nerve serves. It is done in cases of thoracic back pain or pain in the trunk and is a more successful test than an MRI or CT scan of the thoracic spine because a disc severely damaged on CT scan may not be painful while a mildly damaged disc can be the source of the pain.
The test was originally called a diagnostic disc puncture by its originator, Dr. Lindblom. It is done under local anesthesia so that the patient can identify whether or not stimulating the disc causes their pain. After numbing up the suspicious areas, a fine needle is inserted into the back and finally into the disc. The disc is then pressurized with contrast medium, thus expanding the soft disc. The patient is then asked to say if there is pain and if the pressurizing of the disc recreates their exact pain or a different type of pain. If the disc pressurization does not cause the patient’s typical pain, another disc is pressurized. At the end of the procedure, the patient is given a CT scan of the back to look for leakage of contrast medium through radial tears in the disc annulus.
The major risk factor of a thoracic discogram is infection in the disc afterward, which is extremely hard to treat. There is also a risk of puncturing the lung or pleural sac. This is why the procedure should be performed by an expert in the procedure. Fortunately, the procedure has been performed for more than 50 years so experts exist who can identify the disc, pressurize it and can obtain effective answers.
While thoracic disc abnormalities are not that common, there can be degeneration of the thoracic disc and end-plate problems and changes in the disc due to osteophyte formation seen in the middle of the thoracic disc. These can all cause local pain in the mid back or pain in the radicular area, along the trunk or upper abdomen. This kind of pain has been found to be as disabling as low back pain. Facet joint pain in the joints of the thoracic back has been seen in 48 percent of those with thoracic spinal pain without obvious evidence of disc problems.
Interestingly, pain in the discs can mimic visceral pain when no visceral injury exists. In such cases, a thoracic discogram needs to be done in order to identify the offending disc as the real cause of the visceral pain. Disc problems in the lower thoracic area or the thoracolumbar area can feel like gynecological pain and much can be done to work up a nonexistent gynecological problem when the problem is really in the disc.
The important part of having thoracic discography is to have a skilled practitioner do the test so that the side effects and complications can be minimized.