What Is Polymyositis?

Polymyositis is a disease that causes inflammation and weakness of your muscles. The disease commonly afflicts your skeletal muscles, which are responsible for helping you make movements, such as walking. As the disease progresses, your muscles' movements will become inhibited and you'll find it more difficult to do simple tasks, such as lifting an object or standing from a sitting position. According to the National Institute of Neurological Disorders and Stroke, polymyositis commonly afflicts those between the ages of 31 and 60.

Causes

• Inflammatory myopathies are diseases that result in conditions such as polymyositis. The exact cause of inflammatory myopathies is not known. It is possible for infections resulting from bacteria or parasites to cause inflammatory myopathies. In some cases, inflammatory myopathies develop in the same way as autoimmune diseases. Autoimmune diseases develop when your body attacks healthy components within your body. When you have polymyositis, your body triggers autoantibodies to be produced by your immune system, and these autoantibodies attack your healthy tissues. According to the Mayo Clinic, people with polymyositis have autoantibodies in their blood.

Symptoms

• As polymyositis progresses, you'll begin to feel muscle weakness within your limbs. Muscle weakness is most noticeable in your hips, thighs, neck, shoulders and arms. Muscle weakness affects both sides of your body: If you have muscle weakness in your right thigh, your left thigh will be weak as well. Other symptoms of polymyositis include arthritis, difficulty swallowing or speaking, shortness of breath, and exhaustion.

Complications

• Complications such as malnutrition, pneumonia, respiratory problems and calcium deposits can occur with polymyositis. If you develop muscle weakness within your esophagus, problems swallowing food are likely to follow. As a result, you may lose weight and develop malnutrition. Not being able to swallow food properly can also make you aspirate, or inhale food and liquids into your lungs, possibly leading to pneumonia. If you have muscle weakness within your chest, you can develop respiratory failure. Calcium deposits can develop if you've suffered from the disease for long periods of time. The calcium deposits can lead to calcinosis, which are white calcium lumps that form under your skin.

Treatments

• Treatments for polymyositis can improve your quality of life. Corticosteroids can help reduce the production of antibodies within your body, which can then reduce inflammation of your muscles. Intravenous immunoglobulin may also be a course of treatment. According to the Mayo Clinic, this uses healthy antibodies to help suppress antibodies that attack your muscles.

Other Treatments

• Physical therapy may improve your muscle flexibility and range of motion and help you maintain muscle strength. As polymyositis progresses, it may be necessary to have a registered dietitian help you learn how to prepare foods that don't require too much chewing and are easier for you to ingest. Your physician can help you gain access to therapists as appropriate.