Polymyositis

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.

Causes

Experts don't know the exact cause of polymyositis. Having certain gene changes may make people more likely to get the condition.

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.

Treatment

There's no cure for polymyositis. But treatment can improve muscle strength and help muscles work better. Your healthcare professional bases your treatment on your symptoms and how well the treatment manages them.

Medications

The most common medicines to treat polymyositis include:

• Corticosteroids. Medicines such as prednisone can manage polymyositis symptoms well. But using these medicines over time can cause serious side effects, including muscle weakness. So your healthcare professional tapers the dosage little by little.
• Corticosteroid-sparing agents. When used with a corticosteroid, these medicines may allow for a lower dosage of the corticosteroid and fewer side effects. The two most common medicines for polymyositis are azathioprine (Azasan, Imuran) and methotrexate (Trexall, Xatmep).
• Medicines for more-serious illness. Other medicines for polymyositis include mycophenolate mofetil (CellCept, Myhibbin), cyclosporine (Gengraf, Neoral, others), tacrolimus (Astagraf XL, Prograf, others) and rituximab (Rituxan). These medicines can lessen the need for long-term corticosteroids.

• Intravenous immunoglobulin. Also called IVIg, this purified blood product has healthy antibodies from thousands of blood donors. These healthy antibodies can block the antibodies that attack muscle in polymyositis.

  Treatment with IVIg involves getting the medicine through a vein, called an infusion. IVIg treatments may be used regularly or sometimes. The treatment mainly helps with trouble swallowing.

Therapy

Depending on the how serious the symptoms are, treatment might include:

• Physical therapy. A physical therapist can show you exercises to improve your strength and tell you what level of activity is right for you.
• Speech therapy. If polymyositis weakens muscles used for swallowing, speech therapy can help you learn how to work with the weakness.
• Nutrition help. Over time, polymyositis can make it harder to chew and swallow. A registered dietitian can teach you how to make easy-to-eat foods that give you enough nutrition.

Preparing for an appointment

Start by seeing your main healthcare professional, who might send you to a specialist in conditions of the joints, muscles and bone, called a rheumatologist. Or you might see a specialist in conditions of the nervous system, called a neurologist.

What you can do

Make a list of:

• Your symptoms, including when they began and which muscles are affected.
• Key personal information, including major stresses, recent life changes, and your and your family's medical history.
• All medicines, vitamins and other supplements you take, including the dosages.
• Questions to ask your healthcare professional.

For polymyositis, some questions to ask include:

• What is the likely cause of my symptoms?
• What are other possible causes for my symptoms?
• What tests do I need? Do I need to do anything to prepare for them?
• What treatments do you suggest?
• I have other medical conditions. How can I best manage them together?
• Do you have brochures or other printed material that I can have? What websites do you suggest?

Be sure to ask all the questions you have.

What to expect from your doctor

Your healthcare professional may ask you questions, such as:

• Did your symptoms come on slowly or did they start all at once?
• Do you easily tire during waking hours?
• What does your condition keep you from doing?
• Has anyone in your family been diagnosed with a condition that affects the muscles?
• What, if anything, seems to make your symptoms better?
• What, if anything, seems to make your symptoms worse?