Multiple sclerosis (MS) is a chronic disease of the central nervous system characterized by the degeneration and loss of myelin (a white, fatty substance that acts as an electrical insulator for nerve fibers) in the brain stem, optic nerve, spinal cord, and in some cases the cerebrum. There are trends, patterns of the disease MS is not an inherited disease, but a predisposition may run in families. The cause remains unknown, but some researchers propose that it is an autoimmune disorder caused by trama to the body. Others believe a viral infection may trigger the disease. It is more common in temperate climates and is relatively rare in Asia and Africa. In the United States it is usually diagnosed between the ages of 20 and 40. Women are nearly three times more likely to be affected than men. The average life expectancy after onset is about 10 to 20 years, although some patients die within weeks and others survive more than 50 years. Respiratory infections and opportunistic diseases are often among the causes of death in the most severely affected patients. There is no specific treatment for MS In most cases MS follows a course of repeated remissions and worsenings over a period of years. Many patients lead active and productive lives interrupted by periodic episodes of symptoms. Because of lack of persistent symptoms, many MS patients go for a number of years before being correctly diagnosed. Symptoms can be so bizarre that the patient may have a hard time describing them. Patients with MS may suffer, weakness, incoordination, mental disturbances, impaired sensation, and visual problems urine retention and urinary tract infections, constipation, joint contractures, pressure ulcers, and pneumonia. As the disease advances, it may cause blindness, ataxia, incontinence, muscle atrophy, spastic paraplegia, hemiplegia, and complete paralysis. Emotional symptoms, include severe mood swings, irritability, euphoria, and deep depression.