The inflammatory myopathies are a group of diseases, with no known cause, that involve chronic muscle inflammation accompanied by muscle weakness. The three main types of chronic, or persistent, inflammatory myopathy are polymyositis, dermatomyositis, and inclusion body myositis (IBM). These rare disorders may affect both adults and children, although dermatomyositis is more common in children. Polymyositis and dermatomyositis are more common in women than in men. General symptoms of chronic inflammatory myopathy include slow but progressive muscle weakness that starts in the proximal muscles—those muscles closest to the trunk of the body. Other symptoms include fatigue after walking or standing, tripping or falling, and difficulty swallowing or breathing. Some patients may have slight muscle pain or muscles that are tender to the touch. Polymyositis affects skeletal muscles (involved with making movement) on both sides of the body. Dermatomyositis is characterized by a skin rash that precedes or accompanies progressive muscle weakness. IBM is characterized by progressive muscle weakness and wasting. Juvenile myositis has some similarities to adult dermatomyositis and polymyositis.
The chronic inflammatory myopathies can’t be cured in most adults but many of the symptoms can be treated. Options include
medication, physical therapy, exercise, heat therapy (including microwave and ultrasound), orthotics and assistive devices,
and rest. Polymyositis and dermatomyositis are first treated with high doses of prednisone or another corticosteroid drug.
This is most often given as an oral medication but can be delivered intravenously. Immunosuppressant drugs, such as azathioprine
and methotrexate, may reduce inflammation in people who do not respond well to prednisone. IBM has no standard course of treatment.
The disease is generally unresponsive to corticosteroids and immunosuppressive drugs.
Most cases of dermatomyositis respond to therapy. The prognosis for polymyositis varies. Most individuals respond fairly
well to therapy, but some people have a more severe disease that does not respond adequately to therapies and are left with
significant disability. IBM is generally resistant to all therapies and its rate of progression appears to be unaffected
by currently available treatments.
The National Institutes of Health (NIH), through the collaborative efforts of its National Institute of Neurological Disorders
and Stroke (NINDS), National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), and National Institute
of Environmental Health Sciences (NIEHS), conducts and supports a wide range of research on neuromuscular disorders, including
the inflammatory myopathies. The NINDS and NIAMS are funding DNA analyses using microarrays to characterize patterns of muscle
gene expression among adult and juvenile individuals with distinct subtypes of inflammatory myopathies. Findings will be
used to refine disease classification and provide clues to the pathology of these disorders. Other NIH-funded research is
studying prior viral infection as a precursor to inflammatory myopathy. Other research hopes to determine whether the drug
infliximab, which blocks a protein that is associated with harmful inflammation, is safe and effective in treating dermatomyositis
and polymyositis.
American Autoimmune Related Diseases Association 22100 Gratiot Avenue Eastpointe, MI 48201-2227 aarda@aarda.org http://www.aarda.org Tel: 586-776-3900 800-598-4668 Fax: 586-776-3903 |
Myositis Association 1233 20th Street, NW Suite 402 Washington, DC 20036 tma@myositis.org http://www.myositis.org Tel: 202-887-0088 800-821-7356 Fax: 202-466-8940 |
Arthritis Foundation 1330 West Peachtree Street Suite 100 Atlanta, GA 30309 help@arthritis.org http://www.arthritis.org Tel: 800-283-7800 404-872-7100 404-965-7888 Fax: 404-872-0457 |
Muscular Dystrophy Association 3300 East Sunrise Drive Tucson, AZ 85718-3208 mda@mdausa.org http://www.mda.org Tel: 520-529-2000 800-344-4863 Fax: 520-529-5300 |
National Institute of Arthritis and Musculoskeletal
and Skin Diseases Information Clearinghouse 1 AMS Circle Bethesda, MD 20892-3675 NIAMSinfo@mail.nih.gov http://www.niams.nih.gov Tel: 877-22-NIAMS (226-4267) 301-565-2966 (TTY) Fax: 301-718-6366 |
National Institute of Environmental
Health Sciences (NIEHS) National Institutes of Health, DHHS 111 T.W. Alexander Drive Research Triangle Park, NC 27709 webcenter@niehs.nih.gov http://www.niehs.nih.gov Tel: 919-541-3345 |
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Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
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Last updated January 29, 2009