Herniated and Bulging Discs

Do discs slip?
In lay terms, a slipped disc can mean a ruptured disc or herniated disc (her-knee-ate-ed). Although the term slipped disc is used, discs do not slip. Each intervertebral disc is sandwiched between two vertebrae supported by a system of ligaments that help hold the spinal package together.

What is the difference between a bulging and herniated disc?
Disc disorders are contained or non-contained. A bulging disc is an example of a contained disc disorder. A bulging disc has not broken open; the nucleus pulposus (new-klee-us pul-poe-sis) remains contained within the anulus fibrosus (an-you-lus fye-bro-sis). A bulging disc could be compared to a volcano prior to eruption and may be a precursor to herniation. The disc may protrude into the spinal canal without breaking open. The gel-like interior (nucleus pulposus) does not leak out. The disc remains intact except a small bubble pops out attached to the disc.

A non-contained disc is one that has either partially or completely broken open; a herniated or ruptured disc. To illustrate imagine a tube (anulus fibrosus) of toothpaste (nucleus pulposus) placed under pressure. The pressure causes the toothpaste within the tube to move wherever it can. If any part of the tube is weak toothpaste may leak out. When a disc herniates the contents may spread out to the spinal cord and nerves. The disc material has little space to go --- into the area occupied by the spinal canal and nerve roots.

Why might a herniated disc cause pain?
Returning to the leaky tube of toothpaste, the disc's gel-like nucleus contains a chemical that irritates the nerves causing them to swell. After the chemical agent has done its job, the remnants of the chemical remain and continue to press on the irritated and swollen nerves. To complicate matters, sometimes fragments from the anulus (tire-like outer disc wall) break away from the parent disc and drift into the spinal canal. These free fragments may travel in the spinal canal. Depending on the type of injury and the condition of the discs, more than one disc may herniate, rupture, or bulge. Sometimes injury causes a combination of disc disorders.

This article is an excerpt from a book titled Save Your Aching Back and Neck, A Patient's Guide (Second Edition, May 2002, completely revised).