A discography, or discogram, is a diagnostic procedure used to assist in the diagnostic/therapeutic workup of a patient who is having refractory back pain. The “tools” of a pain specialist are the interventions which can be done to diagnose the “pain generator”. This is the structure which is causing the pain. This can be done by blocking the pain, or in this circumstance, by reproducing it. If a patient continues to experience neck or back pain which has not gotten better by more conservative treatments, then this may be recommended.
Unfortunately, an MRI study may be incorrect in determining the condition about 40% of the time. An MRI study is a picture at a static moment in time, done with a patient in a stationary position. Studies have been done where asymptomatic patients (no complaints of back pain) were revealed to have positive MRI findings (disk degeneration, bulges or even herniations) even though they never had a history of back pain – false positive findings. Conversely, discography has shown multiple times there can be painful disks even with a lack of MRI findings – false negative findings. Therefore, it is paramount to determine the true etiology of the condition before more aggressive treatments are undergone.
While no study, including discography, is perfect, it gives much more information than a MRI alone. There are two components: the provocative component, and the radiological component. This test helps determine if the neck or back pain is being caused by one or more of the intervertebral disks. It is used by pain physicians and surgeons to determine the correct treatment for the patient, whether that be a laser (percutaneous) diskectomy, endoscopic assisted diskectomy, or open surgical microdiskectomy or even fusion operation.
The procedure involves placing needles, under anesthesia, into the discs. The patient is then awoken, and conversive. A small amount of contrast is injected under pressure and responses are noted. First, this produces a real time fluoroscopic image of the disk, and the contrast can reveal abnormalities (annular tears etc.) that the MRI may not have been sensitive enough to pick up. Second, as a result of the increased pressure within the disc, the patient may experience pain. Most important is not only that pain may be reproduced, but whether or not it is similar to the usual pain that the patient has been experiencing. The patient, while briefly awake, is given analgesics so as to lessen any negative experience, and some are amnestic as well (don’t remember being awake at all).
Nonetheless, patients undergo this test because it gives invaluable information as part of their care. The test is much more sensitive than an MRI for determining the integrity of the disks, and can determine which disks are provoking pain, something an MRI cannot do. Many times subtle internal diskogenic abnormalities are not visualized on an MRI, but dye leakage out of the disks cannot be missed. Usually a CT scan is then performed, as fluoroscopy is limited in viewing the internal structure of the disks, and where dye leakage has occurred.
In conclusion, provocative discography is an invaluable component of a pain specialist in the workup of a patient with ongoing neck and back pain. It gives real time information utilizing patient feedback, in helping to determine if one or more intervertebral disk are abnormal and symptomatic. The information obtained can either help a patient avoid surgery, or determine what minimally invasive or surgical treatment is most appropriate. It is recommended by many pain specialists and surgeons in the care of their patients.