Overview
Polymyositis (pol-e-my-o-SY-tis) is a condition in which swelling and irritation, called inflammation, happens when the immune system attacks its own muscle tissues. Polymyositis causes weakness of the muscles involved in body movement, called skeletal muscles. Muscle weakness most often happens on both sides of the body at the same time.
The condition, also called an autoimmune condition, isn't common. Having this condition can make it hard to climb stairs, rise from sitting, lift objects or reach up.
Polymyositis most often affects adults in their 40s to 60s. Symptoms tend to come on slowly, over weeks or months.
There's no cure for polymyositis. But treatment can improve muscle strength and help muscles work better. Treatments include medicines and physical therapy.
Symptoms
The muscle weakness of polymyositis most often involves the muscles closest to the central part of the body, called the trunk. It may affect the muscles of the hips, shoulders and neck. Muscles on both sides of the body weaken. In polymyositis, muscle weakness tends to get worse slowly.
When to see a doctor
Make an appointment with a healthcare professional if you get muscle weakness.
Causes
Experts don't know the exact cause of polymyositis. Having certain gene changes may make people more likely to get the condition.
Risk factors
People assigned female at birth have a higher risk of polymyositis than do people assigned male at birth.
Complications
Complications of polymyositis may include:
- Trouble swallowing. The condition may affect the muscles in the tube that carries food from the throat to the stomach, called the esophagus. This can lead to trouble swallowing, called dysphagia. Trouble swallowing may cause weight loss and not getting enough nutrition.
- Aspiration pneumonia. Trouble swallowing may also cause the breathing of food or liquids, including saliva, into the lungs. This is called aspiration and can lead to pneumonia.
- Breathing problems. Polymyositis may affect the chest muscles. This can cause trouble breathing, such as shortness of breath. If breathing is affected enough, it can cause failure of the system that allows breathing, called respiratory failure.
Linked conditions
Polymyositis is often linked with other conditions that may cause more complications. Conditions include:
- Raynaud's disease. This condition causes the fingers, toes, cheeks, nose and ears to turn white, purple or red in response to cold temperatures or stress. Color changes may be harder to see on Black or brown skin. The condition also may cause numbness and tingling.
- Other diseases. Other autoimmune conditions, such as lupus, rheumatoid arthritis, scleroderma and Sjogren syndrome, can happen with polymyositis.
- Cardiovascular disease. Polymyositis may cause the muscular walls of the heart to become inflamed, called myocarditis. A small number of people who have polymyositis may get congestive heart failure and irregular heart rhythms called arrythmias.
- Lung disease. A condition called interstitial lung disease may happen with polymyositis. Interstitial lung disease is a group of conditions that cause scarring of lung tissue. Called fibrosis, the scarring makes lung tissue stiff and thick. This makes it hard for the lungs to expand and fill with air.
- Cancer. People who have polymyositis may have a higher a risk of cancer.