Polymyositis (cont.)
How is polymyositis treated?
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:
Clinical Primer of Rheumatology, Lippincott Williams & Wilkens, edited by William Koopman, et al., 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.
Last Editorial Review: 1/23/2008


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