Polymyositis

One of the conditions we see often is a condition called polymyositis, which is a condition of an inflammation of the muscle groups. It is very similar to a condition called dermatomyositis which is distinguished by not only having muscle involvement, but also by having a typical skin rash around the face, eyes, back of the hands and extremities. Polymyositis may present in childhood, middle age, or old age and, depending on the age, may have different significance. The childhood form is a very serious form, which often causes severe muscle weakness and can be difficult to treat. The elderly form may at times be a sign that there is some underlying more serious condition, such as a malignant condition, and that possibility needs to be looked for carefully. 

The more common type occurring in the young to middle age group relates to an autoimmune disease that causes a fairly progressive onset of pain and weakness in the muscles especially affecting the head and neck, the shoulders and the lower extremities. People who have this condition may notice that they are having difficulty getting off of a chair, getting in and out of a car, and that exerting minimal effort causes significant fatigue in their muscles. The condition is diagnosed by clinical findings as well as by performing some blood tests. The most diagnostic blood test is the CPK which is a measurement of the enzyme produced by muscle breakdown. The higher the CPK level the more inflammation that is on-going in the muscles. The disease activity is directly related to the CPK level. 

The diagnosis can be confirmed by having an electrical study called an EMG or by having a biopsy. The treatment ranges from using corticosteroids to immunosuppressive drugs. In general, the treatment will be very effective especially when the diagnosis is made early. Unfortunately, this diagnosis is often missed until the disease is advanced and has caused severe weakness and muscle wasting. It is also important to recognize that muscles need to be rested and that exercise aggravates this condition. At times this condition can affect organs, such as the heart, in addition to the muscles of the arms and legs.

Author: Norman B. Gaylis, M.D., F.A.C.P., M.A.C.R.