What is degenerative disc disease?


One of the more unfortunate aspects of getting older is that your joints begin to wear out, oftentimes for no good reason. This wear and tear of the joints is not only common in the knees and the hips but also in the spine. The exact reason why the joints of the spine begin to wear out is not known and may be a combination of factors, such as doing a lot of lifting, having a family history of spine problems or having an injury to the spine. This wear and tear is a form of arthritis, which is where the cartilage in the spine joints begins to wear out. Regardless of the cause, it is well known that arthritis of the spine often increases with increasing maturity for no reason that can be identified.

What are the signs of arthritis of the spine?

Most of the time when there is a little arthritis in the spine, the affected person never knows that it has developed. Sometimes the arthritis can be fairly severe and still have no symptoms. When arthritis of the neck becomes a problem, the signs can be pain in the neck and occasionally in the shoulder blades, into the shoulders and down the arm to the hand. When the pain is localized to the neck and the muscles next to the neck (the trapezius muscles), arthritis is usually causing the problem. Sometimes the neck gets irritated enough that the nerves become involved, and when that happens there may be pain that radiates down the arm to the wrist or fingers. Another sign of nerve involvement is tingling and numbness (called paresthesia) in the arm or fingers. Often the tingling and numbness will come and go and generally will not last. However, as the nerves become more involved and damaged, the tingling and numbness will remain. The nerves also make the muscles work, so if you notice muscle weakness or loss of strength, then the nerve damage is enough that you should seek medical attention right away. If the numbness and weakness are progressively getting worse, you should see your physician right away. Rarely arthritis in the neck can be bad enough to start to affect the nerves in the legs, so if you develop weakness in the legs, difficulty walking or trouble with your bowels or bladder, you should notify your physician and be evaluated right away. Most of the time arthritis in the spine is mild and emergency evaluation and treatment is not needed. Arthritis in the low back has similar symptoms and can cause pain in the back and sometimes into the buttocks. Sometimes the pain can radiate into the thighs, and if it does then it could indicate involvement of the nerves. The guidelines for symptoms of tingling, numbness and weakness are the same in the low back and lower extremities as they are for the neck (in the previous paragraph).

Why does arthritis cause these symptoms?

The spine in your body is divided roughly into three regions (Figure 1). The region in your neck area is the cervical spine, the region in your chest is the thoracic spine and the region in your low back is the lumbar spine. The spine is made up of bones, called the vertebrae, and soft spacers between the bones called discs (Figure 2). The vertebrae are made of bone, which is hard and gives the spine rigidity; this is what allows humans to stand upright. The discs are specialized structures that act as shock absorbers between the bones. Since they do not have calcium in them, they cannot be seen directly on X-ray, but they can be seen with magnetic resonance imaging (MRI). The best way to think of discs is as cream-filled donuts, or perhaps as jelly-filled radial tires. The disc outside is tough and firm, like a radial tire, but the inside is filled with a softer, jelly-like substance. This makes the disc compressible, so that the bones do not see so much stress. As you get older, the jelly part of the disc begins to dry up. This may not happen at all, or may happen to one or more discs for reasons not entirely understood. As the disc dries up, the radial tire part starts to collapse. This allows the bones on either side of the disc to get closer together (Figure 3). As the bones get closer together, they experience more and more stress. The joints around the bones also experience too much stress. The bones and the joints react by making spurs (boney growths), and over time these spurs can begin to pinch the nerves that lead to your arm (Figure 3). This pinching of the nerves can cause pain and sometimes the symptoms mentioned above.


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