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Medical Author:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Medical Editor:

Dennis Lee, MD

Dennis Lee, MD

Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

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In this Article

• What is polymyositis?
• What causes polymyositis?
• What are symptoms of polymyositis?
• How does the doctor diagnose polymyositis?
• How is polymyositis treated?
• Polymyositis At A Glance
• Patient Comments: Polymyositis - Symptoms and Signs
• Patient Comments: Polymyositis - Effective Treatments
• Find a local Rheumatologist in your town
• Polymyositis Index

Initially, polymyositis is treated with high doses of corticosteroids. These are medications related to cortisone and can be given by mouth or intravenously. They are given because they can have a powerful effect to decrease the inflammation in the muscles. They usually are required for years and their continued use will be based on what the doctor finds related to symptoms, examination, and muscle enzyme blood test.

Corticosteroids have many predictable and unpredictable side effects. In high doses, they commonly cause an increase in appetite and weight, puffiness of the face, and easy bruising. They can also cause sweats, facial-hair growth, upset stomach, sensitive emotions, leg swelling, acne, cataracts, osteoporosis, high blood pressure, worsening of diabetes, and increased risk of infection. A rare complication of cortisone medications is severe bone damage (avascular necrosis) which can destroy large joints, such as the hips and shoulders. Further, abruptly stopping corticosteroids can cause flares of the disease and result in other side effects including nausea, vomiting, and decreased blood pressure.

Corticosteroids do not always adequately improve polymyositis. In these patients, immunosuppressive medications are considered. These medications can be effective by suppressing the immune response that attracts the white blood cells of inflammation to the muscles. Many types are now commonly used and others are still experimental. Methotrexate (Rheumatrex, Trexall) can be taken by mouth or by injection into the body. Azathioprine (Imuran) is an oral drug. Both can cause liver and bone-marrow side effects and require regular blood monitoring. Cyclophosphamide (Cytoxan), chlorambucil (Leukeran), and cyclosporine (Sandimmune) have been used for serious complications of severe disease, such as scarring of the lungs (pulmonary fibrosis). These also can have severe side effects which must be considered with each patient individually. Treatment with intravenous infusion of immunoglobulins (IVIG) has been shown to be effective in severe cases of polymyositis that are resistant to other treatments. Recent research reports indicate that intravenous rituximab (Rituxan) may be helpful in treating resistant disease.

Patients with calcium deposits (calcinosis) from dermatomyositis can sometimes benefit by taking diltiazem (Cardizem) to shrink the size of the calcium deposits. This effect, however, occurs slowly—frequently over years, and is not always effective. The complication of calcium deposits in muscles and soft tissues occurs more frequently in children than adults.

Physical therapy is an important part of the treatment of polymyositis. When to begin and the continued degree of exercise and range of motion of extremities is customized for each patient.

Patients can ultimately do well, especially with early medical treatment of disease and disease flares. The disease frequently becomes inactive, and rehabilitation of atrophied muscle becomes a long-term project. Monitoring for signs of cancer, heart, and lung disease are essential. Accordingly, EKG, lung function testing, and x-ray tests are used.

As mentioned above, the form of polymyositis called inclusion body myositis is often more resistant to treatment than the usual form of disease. As scientists better define the specific causes of the different forms of polymyositis, treatment will be more accurately aimed at cure of this disease. Researchers are finding more specific antibodies in patients that may be used to diagnose and define active disease.

• Polymyositis and dermatomyositis (PM/DM) are chronic inflammatory diseases of muscle.
• Muscle weakness is the most common symptom of PM/DM.
• The cause of PM/DM is unknown.
• Diagnosis of PM/DM involves physical examination of muscle strength, blood tests for muscle enzymes, electrical tests of muscle and nerves, and confirmed by muscle biopsy.
• Treatment of PM/DM involves high doses of cortisone-related medications, immune suppression, and physical therapy.

For further information about polymyositis, please visit the following site:

Arthritis Foundation (http://www.arthritis.org)
P.O. Box 19000
Atlanta, Georgia 30326
or contact your local chapter.

Additional Organizations to contact:

National Arthritis and Musculoskeletal and Skin Diseases Clearinghouse
Box AMS
Bethesda, Maryland 20892
301-495-4484

References:

Koopman, William, et al., eds. Clinical Primer of Rheumatology. Philadelphia: Lippincott Williams & Wilkins, 2003.

Kelley's Textbook of Rheumatology, W B Saunders Co, edited by Shaun Ruddy, et al., 2000.

American College of Rheumatology, Annual Scientific Meeting; November, 2006, 2007.