(pol-e-my-o-SY-tis) is an uncommon inflammatory disease that causes muscle weakness affecting both sides of your body. Polymyositis can make it difficult to climb stairs, rise from a seated position, lift objects or reach overhead.
Polymyositis most commonly affects adults in their 30s, 40s or 50s. It’s more common in blacks than in whites, and women are affected more often than men. Polymyositis signs and symptoms usually develop gradually, over weeks or months.
While there is no cure for polymyositis, treatment — ranging from medications to physical therapy — can improve your muscle strength and function.
The muscle weakness associated with polymyositis involves the muscles closest to the trunk, such as those in your hips, thighs, shoulders, upper arms and neck. The weakness affects both the left and right sides of your body, and tends to gradually worsen.
The exact cause of polymyositis is unknown, but the disease shares many characteristics with autoimmune disorders, in which your immune system mistakenly attacks your own body tissues.
Possible complications of polymyositis include:
• Difficulty swallowing.
If the muscles in your esophagus are affected, you may have problems swallowing (Dysphagia), which in turn may cause weight loss and malnutrition.
• Aspiration Pneumonia.
Difficulty swallowing may also cause you to breathe food or liquids, including saliva, into your lungs (aspiration), which can lead to Pneumonia.
• Breathing problems.
If your chest muscles are affected by the disease, you may experience breathing problems, such as shortness of breath or, in severe cases, respiratory failure.
• Calcium deposits.
Late in the disease, particularly if you’ve had the disease for a long time, deposits of calcium can occur in your muscles, skin and connective tissues (calcinosis).
Although these are not complications, polymyositis is often associated with other conditions that may cause further complications of their own, or in combination with polymyositis symptoms. Associated conditions include:
• Raynaud’s phenomenon.
This is a condition in which your fingers, toes, cheeks, nose and ears initially turn pale when exposed to cold temperatures.
• Other connective tissue diseases.
Other conditions, such as Lupus, Rheumatoid arthritis, Scleroderma and Sjogren’s syndrome, can occur in combination with polymyositis.
• Cardiovascular disease.
Polymyositis may cause the muscular walls of your heart to become inflamed (Myocarditis). In a small number of people who have polymyositis, congestive Heart failure and Heart arrhythmias may develop.
• Lung disease.
A condition called Interstitial lung disease may occur with polymyositis. Interstitial lung disease refers to a group of disorders that cause scarring (Fibrosis) of lung tissue, making lungs stiff and inelastic. Signs and symptoms include a dry cough and shortness of breath.
TREATMENTS AND DRUGS
Although there’s no cure for polymyositis, treatment can improve your muscle strength and function. The earlier treatment is started in the course of polymyositis, the more effective it is — leading to fewer complications.
However, as with many conditions, no single approach is best; your doctor will tailor your treatment strategy based on your symptoms and how well they respond to therapy.
The most commonly used medications to treat polymyositis include:
Drugs such as prednisone can be very effective in controlling polymyositis symptoms. But prolonged use of these drugs can have serious and wide-ranging side effects, which is why your doctor may gradually taper the dose of medication down to lower levels.
• Corticosteroid-sparing agents.
When used in combination with a corticosteroid, these drugs can decrease the dose and potential side effects of the corticosteroid. The two most common medications used for polymyositis are azathioprine (Azasan, Imuran) and methotrexate (Trexall).
• Rituximab (Rituxan).
More commonly used to treat Rheumatoid arthritis, rituximab is an option if initial therapies don’t adequately control your polymyositis symptoms.
Depending on the severity of your symptoms, your doctor might suggest:
• Physical therapy.
A physical therapist can show you exercises to maintain and improve your strength and flexibility and advise an appropriate level of activity.
• Speech therapy.
If your swallowing muscles are weakened by polymyositis, speech therapy can help you learn how to compensate for those changes.
• Dietetic assessment.
Later in the course of polymyositis, chewing and swallowing can become more difficult. A registered dietitian can teach you how to prepare easy-to-eat foods.
Surgical and other procedures
Intravenous immunoglobulin (IVIg) is a purified blood product that contains healthy antibodies from thousands of blood donors. These healthy antibodies can block the damaging antibodies that attack muscle in polymyositis. Given as an infusion through a vein, IVIg treatments are expensive and may need to be repeated regularly for the effects to continue.