Nucleus pulposus is the thick fluid found within disks in the spine. It acts as a lubricant and a cushion for vertebrae, helping to maintain flexibility in the back and mitigate pressure from walking, jumping, and twisting. The substance tends to gradually degenerate with age, often leading to chronic back pain in older individuals. Back injuries that damage disks and rupture nucleus pulposus can cause the substance to herniate, potentially resulting in severe pain or paralysis.
The primary component of nucleus pulposus is collagen, a gelatin-like collection of protein fibers. Collagen is an important element of muscle and connective tissue throughout the body, but it is especially vital to maintaining a healthy, mobile spine. Water, keratin, and other chemical compounds found in cartilage tissue make up the rest of the substance. The consistency of a disk's nucleus pulposus allows it to act somewhat like a gelled shoe insole: it absorbs impacts and lessens the effects of constant pressure.
A herniated disk occurs when nucleus pulposus bulges from the interior of the disk, slipping it out of alignment in the spine. As a result, the vertebrae on either side of the disk compress together and put pressure on surrounding nerve tissue. Many factors can contribute to a herniated disk, but the most common cause is an acute injury to the spinal cord. A sudden impact from a car crash, an awkward twist while playing a sport, or a fall from height onto the neck or back can all lead to herniation. In addition, age-related degeneration and congenital defects of the spinal cord or nucleus pulposus increase the likelihood of slippage as well.
When a disk does bulge and herniate, it usually causes gradually worsening pain in the back and legs. Without the nucleus pulposus to provide support, vertebrae roughly rub together and cause inflammation. An individual usually has difficulty engaging in activity due to immediate, sharp pains. If nerves are compressed, a person may have numbness or tingling sensations down one or both sides of his or her body. Prompt medical care is important at the first signs of a herniated disk to provide the best chances of recovery.
A specialist can take computerized tomography (CT) scans and magnetic resonance imaging (MRI) screens to identify a herniated disk. If the nucleus pulposus does not appear to be seriously damaged, a patient may simply need to rest and take anti-inflammatory medications to recover from symptoms. Surgery to remove damaged tissue, manually move a disk back into place, or fuse vertebrae together may be necessary in the case of a serious or recurring problem.