Spinal Discs: What They Do and What Can Go Wrong

Spinal discs, also called intervertebral discs, are an important part of the structure of the spine. The bones (vertebrae) of the spine are stacked on top of each other, and between each vertebra is a soft, gel-like cushion called a disc (also spelled "disk").

Discs in the spine serve several functions. They:

• Help absorb the stress created by movement
• Let the spine bend and flex
• Prevent the bones from rubbing against each other.

Degenerative Disc Changes

Each disc has a tough outer layer ("annulus fibrosus") and a soft inner layer ("nucleus pulposus"). Discs are made mostly of water, and as the body ages, it's natural that the discs become dehydrated, causing them to shrink and become less flexible. These degenerative changes do not necessarily cause pain or other problems.

However, if the discs compress the nerves, you can experience ongoing pain, tingling and numbness. This situation is sometimes referred to as "degenerative disc disease," which is not really a disease, but rather a descriptive term for painful disc degeneration. This is also referred to as "discogenic back pain."

Degenerative disc changes may increase your risk of:

• A bulging or herniated disc
• Injury from minor trauma
• Spinal stenosis (a narrowing of the spinal canal).

Other Conditions that Affect Spinal Discs

In addition to degenerative changes, other problems that can occur with the spinal discs are:

• Bulging discs, when the disc protrudes out of the space it normally occupies (but doesn't crack)
• Herniated discs (also called slipped or ruptured discs), when the outer annulus cracks, letting the inner nucleus protrude.

Bulging and herniated discs happen most often in the lumbar spine (lower back). Cervical discs, which are present in the neck, can also herniate. This is a potentially serious problem because the neck has so little space for the spinal cord to pass through, creating a greater risk that the disc could press on the spinal cord and cause injury.

In addition to the effects of aging, other causes of disc problems include:

• Excess body weight, which places extra stress on the lumbar discs
• Improper lifting or repetitive strenuous activities, such as, lifting, pulling, pushing, bending sideways and twisting, which can stress the discs
• Prolonged sitting or standing in one position, which stresses discs
• Smoking, which deprives discs of nutrition and accelerates degeneration
• Traumatic injury.

Treatments for Disc Problems

Treatment for disc problems focuses on relieving pain and other symptoms, and includes most standard treatments for back pain, including exercise, maintaining a healthy lifestyle and rest. In extreme cases—when conservative treatment fails—steroid injections and surgery may be necessary.

Artificial disc replacement is still an experimental procedure not approved by the FDA.

Resources

American Academy of Orthopaedic Surgeons Staff. (n.d.). Herniated disc. Retrieved March 8, 2010, from http://orthoinfo.aaos.org/topic.cfm?topic=A00334

Cedars-Sinai Staff. (n.d.). Degenerative disc disease. Retrieved March 9, 2010, from http://www.cedars-sinai.edu/5757.html

Howard S. An, M.D. (n.d.). Artificial disc replacement. Retrieved March 9, 2010, from http://www.spineuniverse.com/treatments/surgery/artificial-disc-replacement

University of Maryland Medical Center Staff. (n.d.). A patient's guide to anatomy and function of the spine. Retrieved March 1, 2010, from http://www.umm.edu/spinecenter/education/anatomy_and_function_of_the_spine.htm