Spinal Disc Herniation
A slipped disc, in popular usage, is a piece of disc tissue that slips out of place in the spine, causing pressure on a spinal nerve with resulting pain. The term, however, does not correctly reflect the disorder. The correct term is herniated, or ruptured, disc.
A normal intervertebral disc is a relatively soft structure found between the individual vertebrae of the spine. The disc acts as a cushion and shock absorber and serves a definite physiological function in the spine. It is firmly lashed in place and cannot slip, but an abnormality in the structure of the disc can cause the pain of a so-called "slipped disc".
In some individuals a disintegration of the disc occurs with chemical alteration of the structural tissue of the disc. The process resembles premature aging, and there is some evidence that it is familial. This degeneration can take place without the patient being aware of it. The net effect is to convert the relatively soft cushion into fibrous scar tissue that acts as a very poor shock absorber. This type of change occurs most commonly in the lumbar spine, or low back region, but it may also occur in the cervical, or neck, region. As long as the degenerated disc material remains intact, it may cause only back pain, and any associated leg pain is due to muscle irritation. The condition known as herniated disc occurs if the degenerated disc breaks up, allowing a fragment of disc material to move out of place and press on a spinal nerve. A disc also may herniate suddenly when a great effort is made or sometimes even with little strain, such as bending over.
When a true herniated disc occurs in the lower back region, the classic pattern of leg pain due to sciatica presents itself. The patient develops severe leg pain involving the buttock, posterior thigh, back of the knee, and calf, and sometimes extending to the foot. Often, numbness and tingling occur in the foot and toes. The pain is aggravated by activities that raise the spinal fluid pressure, such as coughing or lifting. There may be back pain, but leg pain is the chief complaint. If the herniated disc occurs in the neck region, there may be pain in the shoulder and arm and numbness in the fingers.
Ordinary X rays do not reveal a herniated disc, but an MRI scan can identify this disorder. A physical examination usually reveals the presence of nerve pressure. Many patients recover by bed rest alone. Heat applications and muscle-relaxing drugs often help. If nerve pressure is severe and conservative treatment is not successful, surgical removal of loose disc fragments may be necessary.