Polymyositis (PM)

Causes/Inheritance

In most cases, the cause of an inflammatory myopathy like polymyositis (PM) is unclear. For some reason, the body’s immune system turns against its own muscles and damages muscle tissue in an autoimmune process.

Viruses might be a trigger for autoimmune myositis. People with the HIV virus, which causes AIDS, can develop a myositis, as can people with a virus called HTLV-1. Some myositis cases have followed infection with the Coxsackie B virus.

Diagnosis

As with other muscle diseases, a doctor diagnoses polymyositis (PM) by considering an individual’s history, family medical history and the results of a careful physical examination. This may be followed by some lab tests, perhaps of the electrical activity inside the muscles and usually a muscle biopsy.

Signs and Symptoms

Polymyositis (PM) is more common in females than males and usually begins after age 20. Over a period of weeks or months, several muscles become weak and gradually get weaker. Most affected are the muscles of the hips and thighs, the upper arms, the top part of the back, the shoulder area and the muscles that move the neck.

Many people with PM have pain or tenderness in the affected areas. The person may have trouble extending the knee, stepping down or climbing stairs.

Overview

Muscles affected by polymyositis (frontal view) Muscles affected by polymyositis (back view)
Polymyositis mostly affects the muscles of the hips and thighs, the upper arms, the top part of the back, the shoulder area and the neck.

Polymyositis

Description: 

MDA leads the search for treatments and therapies for polymyositis (PM). The Association also provides comprehensive supports and expert clinical care for those living with PM.

In this section, you’ll find up-to-date information about polymyositis, as well as many helpful resources. This information has been compiled with input from researchers, physicians and people affected by the disease.

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Researchers at the Psychology of Disability Lab at the University of Michigan in Ann Arbor are exploring the social identity of people with disabilities through a short, anonymous, Web-based questionnaire.

The lab's Disability Identity Project is being headed by principal investigator Adena Rottenstein, a doctoral candidate in psychology.

The study closes the week of Aug. 22, 2011.

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