Diagnosing Back Pain From Degenerative Disc Disease
Low back pain from degenerative disc disease can be severe and cause depression, lost time from work, and hinder recreational activities. How does a doctor diagnose the disease? And then how does a doctor guarantee that the problem intervertebral disk is the cause of one's back pain?
The intervertebral lumbar disc is made up of two parts that are analogous to a jelly donut. The inside part, the jelly, is known as the nucleus pulposus and does not cause any pain. The anulus fibrosus is the outer part and does contain nerve endings which, if injured, can cause acute and potentially chronic low back pain.
When a person is experiencing back pain, the work up includes the following.
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History and Physical - Typically the patient has pain located in the low back, and often aggravated while sitting and in flexion posture. Tests have shown positions of flexion actually increase pressure on the lumbar disk.
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Xrays - Plain films are a standard initial imaging work up. Plain x-rays can show degenerative disk disease as a smaller space than usual between the vertebrae so one sees less space between the bones. Hence, this is an indirect diagnosis. Be cognizant that the xrays may show a decrease in the height of the disc reflective of degenerative disc disease but it may not actually be the source of pain.
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MRI - A Magnetic Resonance Image is very good at noticing differences in the soft tissues of the musculoskeletal system. If a lumbar disk is degenerated, the MRI will detect the loss of water and the disc will show up dark on the scan. Additionally, an MRI can sometimes show a tear in the outer part of the intervertebral disc, the anulus. As with x-rays, an MRI can suggest that a lumbar disc that is degenerative may be producing back pain, but may just be an incidental finding.
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Lumbar Discogram - A discogram is a study meant to delineate if the lumbar disk is the source of low back pain. The procedure is performed under sedation, however, the person cannot be completely put out since the pain doctor needs input from the patient during the procedure. Usually a control level is included at a disc level thought to be normal. The pain doctor places the needle into the disk space and injects dye along with the fluid. This injected fluid is designed to raise intradiscal pressure and produce pain from the degenerative disc. There are 3 possible answers. One is the patient has no pain. Two is the patient has pain from the fluid that is unlike what he experiences on a daily basis. That is then measured as a negative study at that level. Three is the person has the same pain he or she experiences every day. That is considered a positive study. A discogram therefore has no therapeutic benefit and is not designed to alleviate pain, it actually creates it! The study serves a diagnostic benefit for pre-operative planning.
Currently the studies utilized to diagnose degenerative disc disease, called DDD, represent the best that modern medicine has to offer. There really isn't one definitive study.
