Polymyositis

What is Polymyositis?

Polymyositis is an inflammatory disorder of skeletal muscle that causes muscle weakness.  The disease has a moderately severe onset and generally begins in the second decade of life, rarely affecting individuals under the age of 18.  The most common symptom is muscle weakness, usually affecting the muscles that are closest to the trunk of the body. Eventually, individuals have difficulty rising from a sitting position, climbing stairs, lifting objects, or reaching overhead.  In some cases, muscles that are further from the trunk of the body may be affected later in the course of the disease.  Individuals may have trouble swallowing.  Muscles may ache and be tender to the touch.  The disease may be associated with other collagen-vascular, autoimmune, or infectious disorders such as Crohn disease, myasthenia gravis, or HIV-AIDS. 

Is there any treatment?

Treatment for polymyositis generally calls for the use of prednisone, a steroid drug.   If prednisone isn’t 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.

What is the prognosis?

The prognosis for polymyositis varies.  Some individuals have severe disease that does not respond adequately to therapies and are left with significant disability. Death from the disorder is rare, but may occur in patients with severe and progressive muscle weakness, difficulty swallowing (dysphagia), malnutrition, pneumonia, or respiratory failure.