Polymyositis is a 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
This rare disease is believed to be an autoimmune disorder. Your immune system is your body’s defense system. It fights diseases and infections. In this case your immune system attacks your own muscle tissue by mistake.
The sooner the disease is treated, the better the outcome. If you suspect you have this condition, contact your doctor.
The cause is unknown. Factors that may contribute to polymyositis include:
- A virus that sets off the condition
- A reaction to certain drugs that set off the condition
The following factors increase your chance of developing polymyositis:
- Age: 50-70 years old
- Sex: women are more likely to develop polymyositis than men
If you experience any of these symptoms, do not assume it is due to polymyositis. These symptoms are quite common. They may be caused by other, less serious, health conditions. If you experience any one of them, see your doctor.
- General weakness (lethargy)
Weakness in the muscles of the hips and shoulders—occurs slowly and gradually over a period of weeks or even months
- This gradual muscle weakness is often the first sign of the disease
- Achy, tender muscles
- Weight loss
- Fatigue after standing or walking
- Trouble rising from a chair
- Great effort needed to climb stairs
- Struggle to lift objects
- Difficulty reaching overhead (eg, unable to comb your hair)
- Trouble with swallowing (when muscles in the front of the neck and throat become involved)—rare
- Difficulty breathing (if it affects the lungs or chest muscles)—quite rare
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 test—to check for autoantibodies (antibodies that attack parts of your body)
- Creatine kinase test—blood test that looks for elevated levels of muscle proteins or enzymes called creatine kinase (CK) (when a muscle is damaged, CK is released into the bloodstream)
- Aldolase test—a blood test that looks for elevated levels of aldolase (a substance released into the bloodstream when a muscle is damaged)
- Electromyogram (EMG)]]> —measures activity of your muscles, often used to help find causes of muscle weakness or damage
- Muscle ]]>biopsy]]> —a small piece of muscle tissue is removed and examined to see if the muscle is damaged in some way
- ]]>Magnetic resonance imaging (MRI)]]> —noninvasive scan, using magnetic waves, of your muscles to see if any muscles are inflamed
There is no cure. Treatment can improve your muscle strength and function. Talk with your doctor about the best plan for you. Treatment options include the following:
- Corticosteroids—taken by mouth to reduce inflammation of the muscles (often the first medications used)
- Immunosuppressants—nonsteroidal anti-inflammatory drugs (NSAIDS)
Exercising your muscles is vital and may include:
- A regular stretching routine for weakened arms and legs
- Light strengthening as the pain lessens and function returns
- Physical therapy—to prevent permanent muscle damage
- Your doctor may also suggest whirlpool baths, heat, and massages
It is important to get enough rest:
- Take frequent breaks
- Limit your activity when needed
American Autoimmune Related Diseases Association
American College of Rheumatology
National Institute of Neurological Disorders and Stroke (NINDS)
The Myositis Association
BC Health Guide, British Columbia Ministry of Health
The Arthritis Society
Getting diagnosed. The Myositis Association website. Available at: http://www.myositis.org/about_myositis/getting_diagnosed.cfm . Accessed September 12, 2005.
Myositis. American Academy of Orthopaedic Surgeons' website. Available at: orthoinfo.aaos.org/fact/thr_report.cfm?thread_id=266&topcategory=about%20orthopaedics. Accessed September 12, 2005.
Myositis FAQ. The Myositis Association website. Available at: http://www.myositis.org/about_myositis/faq_general.cfm . Accessed September 12, 2005.
Polymyositis. The Mayo Clinic website. Available at: http://www.mayoclinic.com/invoke.cfm?id=DS00334 . Accessed September 12, 2005.
Polymyositis–adult. The National Library of Medicine, National Institutes of Health website. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000428.htm . Accessed September 12, 2005.
Polymyositis information page. National Institute of Neurological Disorders and Stroke (NINDS) website. Available at: http://www.ninds.nih.gov/disorders/polymyositis/polymyositis_pr.htm . Accessed September 12, 2005.
Simply stated: the creatine kinase test. Quest. February 2000; 7(1). Muscular Dystrophy Association website. Available at: http://www.mdausa.org/publications/Quest/q71ss-cktest.html . Accessed September 12, 2005.
Treatment. The Myositis Association website. Available at: http://www.myositis.org/about_myositis/treatment_index.cfm . Accessed September 12, 2005.
Last reviewed January 2009 by ]]>Robert Leach, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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