Multiple Sclerosis

Multiple sclerosis is the most common type of demyelinating disease. Usually, it is chronic and relapsing, but about 30 percent of patients have a progressive case. This disease involves the destruction of the myelin sheaths that surround nerve fibers in the spinal cord and brain. It is believed to be an autoimmune disease, meaning that the body's immune system treats the myelin as a foreign substance and destroys it. The damaged myelin is replaced by scar tissue. The nerves under the scar tissue get damaged, too, so control of voluntary muscles decreases.

95 percent of multiple sclerosis cases begin between the ages of 10 and 25 years. The disease affects men and female equally. It also should be noted that people lieving in tropical and subtropical zones have a low risk of multiple sclerosis, while people who live in the north are at a higher risk. Scientists have tried without success to correlate the disease incidence to race, diet, temperature, solar radiation, and geomagnetic latitude. Recent research has pointed to genetics as a cause of multiple sclerosis, but this is uncertain.

The most prevalent symptoms of the disease include blurring of vision, double vision, blindness, tremor of the hands, weaking of extremities, numbness, tingling, pain, slurring of speech, and loss of urinary and bowel control. Examinations of the brains of multiple sclerosis patients have shown no abnormality on the surface. However, cut sections of the brain show many lesions scattered throughout the white matter of the brain, optic nerves, and spinal cord. Acute lesions show a permeation of phagocytes and mononuclear cells on the vessels. The myelin sheaths vary from partial to complete destruction. In severe lesions, there is total destruction of tissue and cyst formation. As the lesions become chronic, "sclerotic plaque (growth of glial cells and fibers)."

Multiple sclerosis does not shorten life span, but no cure has been found. The symptoms are treated with physical, occupational therapy, and certain drugs. Recovery from relapses may speed up with drugs like corticosteroids, and in chronic cases, the frequency of attacks may be decreased with interferon-B.