Degenerative Disc Disease
As we age, everyone will have wearing and degeneration of their spinal discs. This is inevitable. However, not everyone will develop pain or symptoms due to degenerative disc disease. While this is not actually a disease, this is a condition in which a damaged disc causes pain. This can result in a wide range of symptoms, in varying severity.
Spinal discs are like shock absorbers between the bones of the spine and are designed to help the back stay flexible while resisting forces in many different planes of motion. Each disc has two parts: a firm and tough outer layer called the annulus fibrosus, and a soft and jelly-like inner layer called the nucleus pulposus. The outer portion of this layer contains nerves. If the disc tears in this area, it can become quite painful. The inner part of the disc contains proteins that can cause the tissues they touch to become swollen and tender. If these proteins bulge or leak out to the nerves of the outer layer of the disc, they can cause a great deal of pain.
Unlike other tissues of the body, the disc has very low blood supply. Once a disc is injured, it cannot repair itself, and a spiral of degeneration can set in. This can lead to pain, stiffness, and disc collapse, all of which can lead to other spine problems as well.
Several factors can cause discs to become degenerative; the two most important being genetics and age. When we are born, the disc is about 80 percent water. As we age, the disc dries out and doesn’t absorb shock as well. By age 60, most people have some degree of disc degeneration. However, it should be reassuring that not everyone at that age has back pain.
Overview
This condition is a weakening of one or more vertebral discs, which normally act as a cushion between the vertebrae. This condition can develop as a natural part of the aging process, but it may also result from injury to the back.
Disc Wall Tears
Degenerative disc disease typically begins when small tears appear in the disc wall, called the annulus. These tears can cause pain.
Disc Wall Heals
When the tears heal, creating scar tissue that is not as strong as the original disc wall. If the back is repeatedly injured, the process of tearing and scarring may continue, weakening the disc wall.
Disc Center Weakens
Over time, the nucleus (or center) of the disc becomes damaged and loses some of its water content. This center is called the pulposus, and its water content is needed to keep the disc functioning as a shock absorber for the spine.
Nucleus Collapses
Unable to act as a cushion, the nucleus collapses. The vertebrae above and below this damaged disc slide closer together. This improper alignment causes the facet joints – the areas where the vertebral bones touch – to twist into an unnatural position.
Bone Spurs Form
In time, this awkward positioning of the vertebrae may create bone spurs. If these spurs grow into the spinal canal, they may pinch the spinal cord and nerves (a condition called spinal stenosis). The site of the injury may be painful.
Symptoms
Some people experience pain, numbness or tingling in the legs. Strong pain tends to come and go. Bending, twisting and sitting may make the pain worse. Lying down relieves pressure on the spine.