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Myositis

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Dermatomyositis

Inclusion Body Myositis

Polymyositis


Dermatomyositis

What is Dermatomyositis?

Dermatomyositis is one of a group of acquired muscle diseases called inflammatory myopathies. The disease, which has a somewhat severe onset, affects both children and adults. Females are more often affected than males. Dermatomyositis is characterized by a rash accompanying, or more often, preceding muscle weakness. The rash looks like patchy, bluish-purple discolorations on the face, neck, shoulders, upper chest, elbows, knees, knuckles, and back. Some people may also develop calcium deposits, which appear as hard bumps under the skin. The most common symptom is muscle weakness, usually affecting the muscles that are closest to the trunk of the body. Eventually, people have difficulty rising from a sitting position, climbing stairs, lifting objects, or reaching overhead. In some cases, muscles further away from the trunk of the body may be affected later in the course of the disease. Problems with swallowing (dysphagia) may occur. Occasionally, the muscles ache and are tender to the touch. Affected individuals may also feel fatigue and discomfort and experience weight loss or a low-grade fever.

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Is there any treatment?

Prescribing a steroid drug, such as prednisone, is usually the first line of treatment. Immunosuppressants, such as azathioprine and methotrexate, may help those for whom prednisone is ineffective. Further treatment with intravenous immunoglobulin was shown to be effective and safe. Physical therapy is usually recommended to preserve muscle function and prevent muscle wasting.

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What is the prognosis?

Most cases of dermatomyositis respond to therapy. The disease is usually more severe and resistant to therapy in individuals with cardiac or pulmonary problems.

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Organizations

Muscular Dystrophy Association

American Autoimmune Related Diseases Association

Myositis Association

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

National Organization for Rare Disorders (NORD)

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Inclusion Body Myositis

What is Inclusion Body Myositis?

Inclusion body myositis (IBM) is an inflammatory muscle disease characterized by progressive muscle weakness and wasting. The disorder is similar to another inflammatory myopathy called polymyositis. IBM is often the diagnosis for cases of polymyositis that are unresponsive to therapy, but IBM has its own distinctive features. The onset of muscle weakness in IBM is generally gradual (over months or years). Falling and tripping are usually the first noticeable symptoms. For some patients the disorder begins with weakness in the hands causing difficulty with gripping, pinching, and buttoning. IBM occurs more frequently in men than in women and affects both the proximal (closest to the center of the body) and distal (farthest from the center of the body) muscles. There may be weakness of the wrist and finger muscles and atrophy of the quadricep muscles in the legs. Atrophy or shrinking of the forearms is also characteristic. Difficulty swallowing (dysphagia) occurs in approximately half of IBM cases. Symptoms of the disease usually begin after the age of 50, although the disease can occur earlier.

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Is there any treatment?

There is no standard course of treatment for IBM. The disease is unresponsive to corticosteroids and immunosuppressive drugs. Some evidence suggests that intravenous immunoglobulin may have a slight, but short-lasting, beneficial effect in a small number of cases. Physical therapy may be helpful in maintaining mobility. Other therapy is symptomatic and supportive.

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What is the prognosis?

IBM is generally resistant to all therapies, and its rate of progression appears to be unaffected by any currently available treatments.

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Organizations

Myositis Association

American Autoimmune Related Diseases Association

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Polymyositis

What is Polymyositis?

Polymyositis is an inflammatory muscle disease that causes varying degrees of decreased muscle power. The disease has a gradual onset and generally begins in the second decade of life. Polymyositis rarely affects persons under the age of 18. The most common symptom is muscle weakness, usually affecting those muscles that are closest to the trunk of the body (proximal). Eventually, patients have difficulty rising from a sitting position, climbing stairs, lifting objects, or reaching overhead. In some cases, distal muscles (those not close to the trunk of the body) may also be affected later in the course of the disease. Trouble with swallowing (dysphagia) may occur. Very rarely, the muscles ache and are tender to touch. The disease may be associated with other collagen vascular, autoimmune or infectious disorders

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Is there any treatment?

Treatment for polymyositis generally consists of a steroid drug called prednisone. For patients in whom prednisone is not effective, immunosuppressants such as azathioprine and methotrexate may be prescribed. Intravenous immunoglobulin has also helped difficult cases. Physical therapy is usually recommended to avoid muscle atrophy.

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What is the prognosis?

The prognosis for polymyositis varies. Response to therapy varies from very good to satisfactory. Some patients have a more severe disease that does not respond adequately to therapies and are left with significant disability. Death is rare but may occur in patients with severe and progressive muscle weakness, dysphagia, malnutrition, pneumonia, or respiratory failure.

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Organizations

American Autoimmune Related Diseases Association

Muscular Dystrophy Association

Myositis Association

National Organization for Rare Disorders (NORD)

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Myositis