Polymyositis

How to Say It: Polly-my-oh-sigh-tis

by Cynthia M. Johnson, MA

Definition

Polymyositis is a rare disease of the muscles. They become inflamed or swollen. This can lead to severe movement problems.

Front Muscles of Trunk

Causes

This problem may be caused by changes in genes. The changes may cause the immune system to attack muscles.

Risk Factors

Polymyositis is more common in women and people who are 30 to 50 years of age.

The risk of this problem is higher in people who have family members with lupus.

Symptoms

The muscles near the trunk of the body are most affected. Problems may be:

Poor muscle strength in the hips, neck, and shoulders
Muscle pain that gets worse over time
Low energy
Using more effort than usual to climb stairs
Trouble rising from a chair
Problems reaching above the head
Having a dry cough that will not go away
Problems swallowing

Polymyositis can lead to:

Heart failure
Arrhythmia —irregular heart rhythm

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done.

These tests may be done to confirm muscle disease:

Blood tests—to look for signs of muscle breakdown
Electromyogram (EMG)—test electrical activity of the muscle
MRI scan —to look for inflammation
Muscle biopsy —to look for inflammation or damage

Treatment

The disease starts slowly and gets worse over time. There is no cure. The muscles will get weaker and more painful without treatment.

The goal of treatment is to manage symptoms. Choices are:

Medication

Some options are:

Corticosteroids—to ease inflammation
Immunosuppressants—to decrease damage caused by immune system
IV immunoglobulin therapy —special proteins that may help the immune system work better

Support Therapy

Muscle weakness can cause a loss of function. Therapy may help. Options are:

Physical therapy to help with strength and range of motion
Occupational therapy to help with daily tasks and self care
Speech therapy to improve swallowing and speech

Prevention

There are no guidelines to prevent this health problem.

RESOURCES:

American Autoimmune Related Diseases Association
http://www.aarda.org

The Myositis Association
http://www.myositis.org

CANADIAN RESOURCES:

The Arthritis Society
http://www.arthritis.ca

Health Canada
https://www.canada.ca

References:

Diagnosis. The Myositis Association website. Available at:
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Accessed January 25, 2021.

Idiopathic inflammatory myopathy. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/idiopathic-inflammatory-myopathy. Accessed January 25, 2021.

Milone M. Diagnosis and Management of Immune-Mediated Myopathies. Mayo Clin Proc. 2017 May;92(5):826-837.

Myositis. Ortho Info—American Academy of Orthopaedic Surgeons website. Available at:
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Accessed January 25, 2021.

Polymyositis information page. National Institute of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/Disorders/All-Disorders/Polymyositis-Information-Page. Accessed January 25, 2021.

Treatment and disease management. Myositis Association website. Available at:
...(Click grey area to select URL)
Accessed January 25, 2021.

Types of myositis. Myositis Association website. Available at:
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Accessed January 25, 2021.

Last reviewed December 2020 by EBSCO Medical Review Board Rimas Lukas, MD
Last Updated: 1/25/2021