Inflammatory Myopathies

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
National organization that works to alleviate suffering and the socioeconomic impact of autoimmunity. Dedicated to the eradication of autoimmune diseases through fostering and facilitating collaboration in the areas of education, research, and patient services.

22100 Gratiot Avenue
Eastpointe, MI 48021-2227
Tel: Eastpointe
Fax: 586-776-3903

Myositis Association
Works to improve the lives of those affected by inflammatory myopathies. Seeks out persons with inflammatory myopathies, provides a support network, acts as a resource for patients and the medical community, advocates for patients, and promotes research into the causes and treatment of the disorders.

1737 King Street
Suite 600
Alexandria, VA 22314
Tel: Alexandria
Fax: 202-466-8940

Arthritis Foundation
Volunteer-driven organization that works to improve lives through leadership in the prevention, control, and cure of arthritis and related diseases. Offers free brochures on various types of arthritis, treatment options, and management of daily activities when affected.

P.O. Box 7669
Atlanta, GA 30357
Tel: Atlanta
Fax: 404-872-0457

Muscular Dystrophy Association
Voluntary health agency that fosters neuromuscular disease research and provides patient care funded almost entirely by individual private contributors. MDA addresses the muscular dystrophies, spinal muscular atrophy, ALS, Charcot-Marie-Tooth disease, myasthenia gravis, Friedreich's ataxia, metabolic diseases of muscle, and inflammatory diseases of muscle, for a total of more than 40 neuromuscular diseases.

National Office - 222 S. Riverside Plaza
Suite 1500
Chicago, IL 60606
Tel: Chicago
Fax: 520-529-5300

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NINDS Disorders is an index of neurological conditions provided by the National Institute of Neurological Disorders and Stroke. This valuable tool offers detailed descriptions, facts on treatment and prognosis, and patient organization contact information for over 500 identified neurological disorders.

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