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Definition

Polymyositis is a rare disease of the muscles. It usually affects the muscles closest to the trunk of the body. However, it may affect muscles anywhere in the body. The muscles become inflamed or swollen. This causes pain. The disease is progressive and starts slowly. If untreated, the muscles gradually become weaker. The pain in the muscles also increases.

Front Muscles of Trunk
Trunk Core Muscles
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Causes

Polymyositis may be caused by a combination of genetic and environmental factors that trigger an abnormal immune response.

Risk Factors

Polymyositis is more common in women, and in people aged 31-60 years old.

Symptoms

Polymyositis may cause:

  • Muscle weakness
  • Muscle pain
  • Fatigue
  • Great effort needed to climb stairs
  • Trouble rising from a chair
  • Difficulty reaching overhead
  • Chronic dry cough

Diagnosis

This diagnosis is not easy. Symptoms vary from person to person. It is often a matter of ruling out other diseases and conditions. Your doctor will ask about your symptoms and medical history. A physical exam will be done.

Tests may include the following:

  • Blood tests to check for elevated muscle enzymes and autoimmune antibodies
  • Electromyogram (EMG) to measure muscle activity
  • Muscle biopsy

Imaging tests take pictures of internal body structures to look for muscle inflammation. This can be done with an MRI .

Treatment

While there is no cure, treatment can improve your muscle strength and function. Talk with your doctor about the best plan for you. Options include:

Medication

Medications to treat polymyositis may include:

  • Corticosteroids to reduce inflammation
  • Topical steroids to treat skin rash
  • Immunosuppresants

IV immunoglobulin therapy is another treatment option. It involves using an IV needle to inject extra immunoglobins (special proteins) into the body. This process may help the immune system function better and reduce inflammation.

Physical Therapy

Your doctor may recommend that you work with a physical therapist to prevent permanent muscle damage. Exercise may include:

  • A regular stretching routine for weakened arms and legs
  • Light strengthening as the pain lessens and function returns

Dietary Changes

Polymyositis can lead to problems with chewing and swallowing. By working with a registered dietitian, you can learn ways to adjust to these changes and get the nutrition that you need.

Speech Therapy

Polymyositis may also cause speech problems. A speech therapist can assess your condition and create a program for you.

Prevention

There are no current guidelines to prevent polymyositis.

Revision Information

  • American Autoimmune Related Diseases Association

    http://www.aarda.org

  • The Myositis Association

    http://www.myositis.org

  • Health Canada

    http://www.hc-sc.gc.ca

  • The Arthritis Society

    http://www.arthritis.ca

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  • Myositis. American Academy of Orthopaedic Surgeons Ortho Info website. Available at: http://orthoinfo.aaos.org/topic.cfm?topic=A00198 . Updated July 2007. Accessed July 31, 2013.

  • Myositis Association. Getting diagnosed. The Myositis Association website. Available at: http://www.myositis.org/learn-about-myositis/diagnosis . Updated March 2012. Accessed July 31, 2013.

  • Myositis Association. Myositis FAQ. Myositis Association website. Available at: http://www.myositis.org/learn-about-myositis/types-of-myositis . Updated March 2012. Accessed July 31, 2013.

  • Myositis Association. Treatment. Myositis Association website. Available at: http://www.myositis.org/learn-about-myositis/treatment . Updated March 2012. Accessed July 31, 2013.

  • NINDS Polymyositis information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/polymyositis/polymyositis.htm . Updated August 26, 2011. Accessed July 31, 2013.

  • Simply stated: the creatine kinase test. Quest . 2000;7(1).