Polymyositis - adult
Polymyositis is a rare inflammatory disease. It leads to muscle weakness, swelling tenderness, and tissue damage. It is part of a larger group of diseases called myositis.
Causes
Polymyositis affects the skeletal muscles. It is also known as idiopathic inflammatory myopathy. The exact cause is unknown, but it may be related to an autoimmune reaction or infection.
Autoimmune
An autoimmune disorder occurs when the body's immune system attacks and destroys healthy body tissue by mistake. There are more than 80 types of aut...
Polymyositis can affect people at any age. It most common in adults between ages 50 and 70, and in children ages 5 to 15. It affects women twice as often as men. It is more common in African Americans than Caucasians.
Symptoms
Polymyositis is a systemic disease. This means it affects the whole body. Muscle weakness and tenderness can be signs of polymyositis. A rash is a sign of a similar condition, dermatomyositis .
Dermatomyositis
Dermatomyositis is a muscle disease that involves inflammation and a skin rash. It is a type of inflammatory myopathy.
Common symptoms include:
- Muscle weakness in the shoulders and hips. This can make it hard to raise the arms over the head, get up from a sitting position, or climb stairs
- Difficulty swallowing
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Muscle pain
Muscle pain
Muscle aches and pains are common and can involve more than 1 muscle. Muscle pain also can involve ligaments, tendons, and fascia. Fascia are the s...
- Problems with the voice (caused by weak throat muscles)
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Shortness of breath
Shortness of breath
Breathing difficulty may involve:Difficult breathingUncomfortable breathingFeeling like you are not getting enough air
You may also have:
- Fatigue
- Fever
- Joint pain
- Loss of appetite
- Morning stiffness
- Weight loss
Exams and Tests
Tests may include:
- Autoimmune antibodies and inflammation tests
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CPK
CPK
Creatine phosphokinase (CPK) is an enzyme in the body. It is found mainly in the heart, brain, and skeletal muscle. This article discusses the test...
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Electromyography
Electromyography
Electromyography (EMG) is a test that checks the health of the muscles and the nerves that control the muscles.
- MRI of affected muscles
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Muscle biopsy
Muscle biopsy
A muscle biopsy is the removal of a small piece of muscle tissue for examination.
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Myoglobin in the urine
Myoglobin in the urine
The myoglobin urine test is done to detect the presence of myoglobin in urine. Myoglobin can also be measured with a blood test.
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Serum aldolase
Serum aldolase
Aldolase is a protein (called an enzyme) that helps break down certain sugars to produce energy. It is found in high amount in muscle tissue. A test...
People with this condition also must be watched carefully for signs of cancer.
Treatment
The main treatment is with corticosteroid medicines. The dose of medicine is slowly tapered off as muscle strength improves. This takes about 4 to 6 weeks. You will stay on a low dose of a corticosteroid medicine after that. Medicines to suppress the immune system may be used for people who do not respond to corticosteroids.
Intravenous gamma globulin has been tried, with mixed results. Biologic drugs also may play in part in treating this condition but it is too soon to know. Rituximab appears to be the most promising.
If the condition is associated with a tumor , it may improve if the tumor is removed.
Tumor
A tumor is an abnormal growth of body tissue. Tumors can be cancerous (malignant) or noncancerous (benign).
Outlook (Prognosis)
Response to treatment varies based on the complications. As many as 1 in 5 people may die within 5 years of having the condition.
Many people, especially children, recover from the illness and do not need ongoing treatment. For most adults, however, immunosuppressant drugs are needed to control the disease.
In adults, death may result from:
- Malnutrition
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Pneumonia
Pneumonia
Pneumonia is a breathing (respiratory) condition in which there is an infection of the lung. This article covers community-acquired pneumonia (CAP). ...
- Respiratory failure
- Severe, long-term muscle weakness
The major causes of death are cancer and lung disease.
Possible Complications
Complications may include:
- Calcium deposits in the affected muscles, especially in children with the disease
- Cancer
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Heart disease,
lung disease
, or abdominal complications
Lung disease
Lung disease is any problem in the lungs that prevents the lungs from working properly. There are three main types of lung disease:Airway diseases -...
When to Contact a Medical Professional
Call your health care provider if you have symptoms of this disorder. Seek emergency treatment if you have shortness of breath and difficulty swallowing.
References
Greenberg SA. Inflammatory myopathies. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 69.
Nagaraju K, Lundberg IE. Inflammatory Diseases of Muscle and Other Myopathies. In: Firestein GS, Budd RC, Gabriel SE, et al, eds. Kelley's Textbook of Rheumatology . 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 85.
Oddis CV, Reed AM, Aggarwal R, et al. Rituximab in the treatment of refractory adult and juvenile dermatomyositis and adult polymyositis: a randomized, placebo-phase trial. Arthritis Rheum . 2013; 65:314. PMID: 23124935 www.ncbi.nlm.nih.gov/pubmed/23124935 .
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Superficial anterior muscles - illustration
Superficial muscles are close to the surface of the skin. Muscles which lie closer to bone or internal organs are called deep muscles.
Superficial anterior muscles
illustration
Review Date: 1/20/2015
Reviewed By: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.