Muscular dystrophy refers to any one of a group of muscle diseases in which there is a recognizable pattern of inheritance. They are marked by weakness and wasting of selected muscles. The affected muscle fibers degenerate and are replaced by fatty tissue. The dystrophies are classified according to the patient's age at onset, distribution of the weakness, progression of the disease, and mode of inheritance.

Facts About Polymyositis
Polymyositis involves inflammation -- swelling or irritation -- of the voluntary muscles, those that normally govern movement, such as the muscles of the arms and legs. Myositis means inflammation of muscle. Polymyositis means inflammation of many muscles. The results of this condition is weakened muscles and often muscle pain. Thise condition is seldom fatal, but in the most severe cases a person may need a wheelchair or require assistance with activities of daily living. The muscle inflammation in this form of myositis results from a disturbance in the body's immune system, the mechanisms that normally protect the body against infection and foreign substances. MDA-funded scientists are coming closer to understanding the many factors involved.