Polymyositis - Causes, Symptoms, Treatment
Polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM) are the major members of a group of skeletal muscle diseases called the idiopathic inflammatory myopathies. Clinical features, characteristic muscle biopsy findings, immune markers, and histopathologic findings differentiate these illnesses. No strictly defined diagnostic criteria for PM or DM exist; however, Bohan and Peter proposed the criteria most widely cited. These criteria include the typical rash of DM, findings at history and physical examination that reveal symmetric proximal muscular weakness, elevated serum muscle enzyme levels, electromyographic evidence of myopathic abnormalities, and characteristic findings at muscle biopsy.
This inflammatory form of muscle disease is often associated with arthritis. Because it is a systemic condition that affects all muscles- including those that are responsible for the functioning of the heart, lungs, etc., careful examination and appropriate aggressive medical therapy are necessary.
Causes
To date, no cause of polymyositis has been isolated by scientific researchers. There are indicators of heredity (genetic) susceptibility that can be found in some patients. There is indirect evidence of infection by a virus that has yet to be identified in a form of polymyositis that is particularly resistant to treatment, called inclusion body myositis.
A disease similar to polymyositis is dermatomyositis. Dermatomyositis leads to many of the same symptoms as polymyositis, but it causes skin inflammation or a rash as well. Some other inflammatory muscle diseases are: inclusion body myositis, which progresses more slowly than other forms; myositis associated with other connective tissue diseases, such as lupus or scleroderma; and myositis associated with cancer.
Symptoms
Weakness of the muscles of the hips, thighs, upper arms, top part of the back, shoulders and muscles that move the neck; pain or tenderness in affected areas; possible heart, respiratory and swallowing problems.
Muscle weakness may start slowly or suddenly and may worsen for weeks or months. Because muscles close to the center of the body are affected most, tasks such as lifting the arms above the shoulders, climbing stairs, and getting out of a chair can become very difficult. If the neck muscles are affected, even raising the head from a pillow may be impossible.
Treatment
There is no cure for polymyositis, but the symptoms can be treated. Options include medication, physical therapy, exercise, heat therapy (including microwave and ultrasound), orthotics and assistive devices, and rest. The standard treatment for polymyositis is a corticosteroid drug, given either in pill form or intravenously. Immunosuppressant drugs, such as azathioprine and methotrexate, may reduce inflammation in people who do not respond well to prednisone. Periodic treatment using intravenous immunoglobulin can also improve recovery. Other immunosuppressive agents used to treat the inflammation associated with polymyositis include cyclo.
