What is disc herniation?
A definition of the herniated disc is a condition when the nucleus pulposus, the gel-like inner substance of an intervertebral disc, breaks through the annulus fibrosus, the tough outer rim of the tire-like structure. Pain is the most common symptom. However, nerve compression and inflammation can cause other symptoms, including numbness, tingling, and/or weakness in the extremities.
To better understand what happens when a herniated disc occurs, it is helpful to know a little about the anatomy of the vertebrae themselves and the different parts of the body that make up the spinal column. In between each of your vertebrae is a cushion that acts as a shock-absorber. These are called intervertebral discs. They are sometimes compared to jelly doughnuts.
Each disc has a tough outer ring made up of fibers, which is a strong ligament that binds the vertebra together. This outer rim is called the annulus, and it is the strongest part of the disc. The center of each disc, called the nucleus pulposus, is filled with a gel-like substance. This soft center gives the discs their ability to act as shock-absorbers. When a herniated disc occurs, the tough outer rim is damaged, and the soft gel center moves out of its normal space. If the rim is damaged near the spinal canal, the gel material can bulge out and press into the spinal nerves or the spinal cord.
Causes of disc herniation
The primary causes of herniated disc occur due to normal wear-and-tear on the spine and the process of aging. As we grow older, the discs between our vertebrae are negatively affected by changes that cause them to dry out and lose some of their elasticity. This is usually a slow process, and the herniated disc develops gradually. Occasionally, events occur that cause a herniated disc to happen suddenly. Examples of these events are trauma, such as falls, or other injuries, such as car accidents. Lifting or twisting are other examples of events that can cause a sudden herniated disc.
Most cases of true herniated discs occur in middle-aged and young adults. Children can develop herniated discs, but this happens rarely. In the elderly, degenerative changes in the spine that normally occur with age make it less likely for a true herniated disc to develop.
A herniated disc can occur if too much pressure is suddenly placed on a disc. One example of this can be falling from a tree and landing on the buttocks. This type of fall causes a significant amount of force to be placed on the spine all at once. If enough force is experienced, either a vertebra can break or fracture, or a herniated disc can result. Bending from the waist also places extreme force on the intervertebral discs. If you try to lift a heavy object while bending, the combination of these forces can cause a herniated disc.
A small amount of force can also cause a herniated disc. When this occurs, it is usually due to weakening in the fibrous rim of the disc (the annulus) from a repeated trauma that has added up over time. As the annulus becomes weaker, eventually, too much force or pressure is applied, which herniates due to its weakened condition. You may be lifting or bending in a way that has never caused a problem before, but the aging process of the spine causes a herniated disc. Herniated discs cause problems for two reasons.
First, the gel-like substance that leaks into the spinal canal from the nucleus pulposus can exert pressure on the spinal nerves. There is also a possibility that this gel-like material released by the herniated disc causes a chemical irritation of the nerve roots. The pressure, combined with the irritation, can cause the nerve roots not to function correctly. The result of the herniated disc is pain and/or numbness and weakness in the portion of the body served by the affected nerve.
Pain in the lower back can develop for many different reasons. People use the terms “slipped disc” and “ruptured disc” very frequently, and it is often assumed that every person who has pain in their back has a ruptured or herniated disc. However, a true herniated nucleus pulposus, the medical term for a ruptured disc, is not a common medical problem. In fact, most disorders that cause back pain are due to something other than a herniated disc. In general practice clinics, the overall incidence of true herniated nucleus pulposus in patients who seek medical care due to new symptoms of lower back pain is less than 2%.
Herniated disk complications
Cauda equina syndrome is probably the most severe complication of a herniated disc. This syndrome results when a large portion of the herniated disc material ruptures into the spinal canal where the nerves travel controlling bowel and bladder function. Permanent damage to these nerves can result from pressure. If this happens, you may become incontinent (lose control) of bowel and bladder function. This is a rare but serious condition resulting from a herniated disc. If your physician suspects this is happening, he will recommend immediate surgery to get the pressure off the nerves.
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