Discography is used for chronic deep-seated back pain that allows conclusions to be drawn about discogenic (disc-related) causes. Under X-ray guidance, degenerative changes in the disc are visualized using a contrast agent.
What is discography?
Discography (also discography) is a radiographic diagnostic procedure used to visualize intervertebral discs (discus or discus intervertebralis) using a contrast agent injected intradiscally. Discography (also discography) is an X-ray-based diagnostic procedure for imaging intervertebral discs (discus or discus intervertebralis) using an intradiscally injected contrast medium. With the aid of this procedure, the site of origin of disc-related back pain (discogenic pain syndrome, discopathy) can be precisely localized on the basis of the radiographically documented contrast medium distribution, and degenerative or age-related changes in the affected disc can be detected. As a result of degenerative processes on the intervertebral disc, painful fissures (tears) can develop on the outer fibrous ring of the intervertebral disc and/or disc protrusions (disc bulges). In most cases, the lumbar spine is affected by such injuries to the inner disc architecture. Pain radiates from within the disc via nerve fibers growing into the disc structures as the condition progresses. Morning back pain caused by prolonged recumbency and pain from overloading the back may be signs of disc degeneration and require discography.
Function, effect, and goals
A discography is often used in advance of minimally invasive surgical procedures on the spine (disc prosthesis, spondylodesis) for planning as well as diagnosis confirmation. Here, the examination procedure serves to precisely determine the vertebral segments to be operated on. In addition, the information obtained by discography can facilitate and support the choice of therapy for chronic deep-seated back pain (including intradiscal electrothermal therapy or surgical intervention), which can be attributed to pathological disc changes. The minimally invasive examination can be performed under inpatient or outpatient conditions, and anesthesia is not required or even undesirable. Under local anesthesia, a probe or thin needle (cannula) is inserted into the side of the disc space (space between two adjacent vertebrae in which the disc is located) of the patient lying on his stomach and in twilight sleep. A radiopaque contrast medium – saline solution if the patient is allergic to the contrast medium – is then injected into the gelatinous nucleus of the intervertebral disc (nucleus pulposus). The contrast medium is made visible in its course in several planes by a movable X-ray device (image converter). On the basis of the contrast medium distribution in the nucleus of the intervertebral disc, on the one hand the correct positioning of the probe or cannula is checked and on the other hand an assessment of the condition of the intervertebral disc as well as the extent and type of degenerative changes is made possible. For example, if there is an intact fibrous ring (annulus fibrosus) surrounding the disc, the contrast agent remains in the disc, while leakage of the agent from the disc space indicates a porous or ruptured annulus fibrosus due to disc herniation. A fibrous ring protruding posteriorly into the spinal canal (spinal cord canal), which can lead to pain symptoms in the back and legs due to compression of one or more nerve roots, can also be visualized during discography. The fact that the usual pain can also be provoked or intensified by the administration of contrast medium via the increase in pressure in the disc (discographic distension test) is an additional significant effect (so-called memory pain effect) that supports the localization of the spinal segment affected by degenerative processes. Subsequent injection of an anesthetic that eliminates this pain can provide additional support for the diagnosis. Following discography, an anti-inflammatory and pain-reducing drug is injected through the disc cannula to reduce inflammatory substances in the treated disc.
Risks, side effects and dangers
Since only twilight sleep anesthesia is required for discography and the examination is also performed under X-ray control, serious complications or side effects are generally not to be expected. Despite the local anesthetic applied, many patients find the lateral puncture of the disc to be examined extremely unpleasant. In addition, there is a risk of secondary bleeding if blood vessels are injured. Regardless of the continuous position control by the image converter, a nerve root can also be injured by the cannula in very rare cases. In addition, even with minimally invasive procedures (bacterial) germ spread into the disc space, which can cause a diszitis (painful inflammation of the intervertebral disc), can not be completely excluded. In the case of an allergy to contrast media that is not known in advance, discography due to the injection of contrast media can lead to allergic reactions of varying severity, up to and including anaphylactic shock. Because the distension test is based on subjectively perceived pain that cannot be verified by the examiner, discography can lead to false positive or false negative results.
