The bones of the spinal column (vertebrae) are separated from each other by pad-like structures called discs.  These pads resemble vitamin e capsules; they have a tough elastic exterior  that surrounds a soft, fluid center.  The spinal cord runs just over the disc in a bony tunnel through the vertebrae.  When something happens to weaken the elastic exterior of the disc, the shape becomes altered and a bulge occurs, much like the bubble you would see in an inner tube of a tire.  When the bulge pushes upward and into the bony tunnel containing the spinal cord, an increase in pressure occurs and the actual spinal cord starts getting squeezed; hence the term, pinched nerve.  In more severe conditions, the bubble can actually rupture and release the fluid contents of the disc directly into the tunnel.  Not only does this disc material take up space in the tunnel, but it also causes a severe inflammation, which further squeezes the spinal cord.  The severity of symptoms is related to the degree of spinal cord compression.  Mild bulging of the disc produces pain but as the pressure in the tunnel increases numbness and weakness become apparent and in the most extreme cases, total paralysis can ensue. A less severe problem known as spondylitis can also affect the back.  Also known as spinal arthritis, this condition occurs when there is a lack of stability between adjacent vertebrae, and the body produces extra bone in an attempt to unite the unstable bones.  Typically, symptoms of stiffness and difficulty getting up occur with this condition.

In order to diagnose the problem, x-rays of the spinal column need to be taken.  Very often a sedative will need to be given prior to the films to insure adequate muscle relaxation, which will allow an accurate evaluation of the disc spaces.  In some cases, a myelogram (an x-ray combined with an injection of dye around the spinal cord) will need to be done to pinpoint the exact location of a problem prior to surgery.