Degenerative Disk Disease
Degenerative disc disease involves arthritic changes to the outer portion of the disc (annulus fibrosus) and the inner nucleus (nucleus pulposus).
Before we go any further with this discussion, it should be noted that there are probably more people with degenerative disc disease without back pain than people with degenerative disc disease (DDD) with back pain. It should also be noted that even with people who do experience back pain as a result of DDD, many people experience the most pain while the changes are taking place, and often go into long periods of dormancy (pain free) after the body's various stabilization mechanisms take over. In other cases, the stabilization mechanisms themselves may be painful, in cases where the development of osteophytes (bone spurs) and muscle spasms occur. In other cases, the body's attempt stabilization mechanisms fail to prevent back pain and other symptoms, such as when pieces of the disc impact the spinal canal or nerve roots exiting the spinal cord. Let's take a look at what causes degenerative disc disease.
There are several back conditions that fall under the umbrella of degenerative disc disease - where pathology to the intervertebral discs of the spine wear out to the point where the spinal bones or other tissues of the spine are adversely affected. Degenerative disc disease either involves degenerative changes to the outside of the disc (annulus fibrosus) or the more liquid inner part of the disc (nucleus pulposus). When a person is young and close to their physical prime, the tough outer envelope of the annulus is very strong and multilayered, and the gel-like material in the nucleus has enough water content and volume to fully support the weight of the spine, which takes on added pressures as we sit upright and stand.
As we get older, small tears in the annulus develop, and the inner part of the disc begins to lose its ability to take on and retain water. Degenerative disc disease may occur if either of these two changes take place. The loss of volume in the interior of the disc may have the effect of flattening the disc. If the annulus becomes torn or worn out to certain point, the wall may bulge outwards, becoming a condition known as a bulging disc. If the tear opens to the point where it can no longer retain the materials of the nucleus, the condition may be known as a herniated disc. With a herniated disc, the tear has opened up to a point where a portion of the nucleus has oozed out into the space around the disc.
We may or may not experience pain as a result of a bulging disc or herniated disc. If the outer wall of the disc, as a result of a bulging disc, or the inner core press into spinal structures such as the nerve root of the spine or one of the spinal ligaments, we may indeed experience pain ranging from mild discomfort to severe pain. If the results of the bulging or herniated disc don't involve the spinal ligaments or nerve roots, we may in fact experience no symptoms at all. This last statement is backed by research studies in which large percentages of patients with no history of back pain presented with bulging and herniated discs upon MRIs. MRIs are medical imaging studies that show very good definition and contrast of the soft tissues of the spine, including the intervertebral discs, spinal cord, nerve roots, tendons and ligaments.
Until recently, it was thought that patients with degenerative disc disease only experienced pain when the spinal ligaments or nerve roots were affected. It was thought that the discs themselves were not ever a cause of pain because they were not supplied with pain-sensitive nerves. Today, it is though that the discs themselves can cause pain, and that they do have their own supply of nerves. Medical terms such as discitis and discogenic pain relate to patient symptoms of back pain involving the discs themselves.
Treatment options for degenerative disc disease include physical therapy, injections to block the transmission of pain signals, and surgery to remove part or all of a degenerated disc. Surgical options include procedures such as cervical corpectomy, dynamic destabilization, and percutaneous disc decompression.