Polymyositis (pol-e-my-o-SY-tis) is a rare inflammatory disease that causes muscle weakness. Sometimes, the effects of polymyositis can also involve the lungs.
Most often, polymyositis affects muscles closest to the trunk on both sides of your body. In addition to the larger muscles of your arms and legs, polymyositis can weaken muscles in your throat and chest, creating the potential for complications involving your lungs.
Breathing problems may develop if your chest muscles are affected by the disease, and in severe cases, can lead to respiratory failure. Aspiration pneumonia can develop if difficulty swallowing causes you to inhale food or liquids, including saliva, into your lungs (aspiration).
Polymyositis is often associated with other conditions that may cause complications of their own. Interstitial lung disease causes scarring (fibrosis) of the lung tissue, making lungs stiff and inelastic. Signs and symptoms include a dry cough and shortness of breath.
If you have these symptoms, evaluation of your lung function may include pulmonary function tests and imaging studies may be recommended, such an X-ray or a computerized tomography (CT) scan of your lungs. A swallowing study may be helpful in diagnosing aspiration.
There is no cure for polymyositis, but treatment to control the disease can lessen the likelihood it will affect your lungs. Talk to your doctor about medications that can help control your symptoms.
If you are already experiencing lung symptoms, certain therapies can help. Your doctor might suggest:
- Speech therapy, which can help you learn how to compensate for swallowing muscles weakened by polymyositis
- A dietetic assessment so that a registered dietitian can teach you how to prepare foods that are easy to chew and swallow
April 21, 2020
- Polymyositis information page. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/All-Disorders/Polymyositis-Information-Page. Accessed April 24, 2017.
- Malik A, et al. Idiopathic inflammatory myopathies: Clinical approach and management. Frontiers in Neurology. 2016;7:1.
- Miller ML. Initial treatment of dermatomyositis and polymyositis in adults. https://www.uptodate.com/home. Accessed April 24, 2017.
- Miller ML, et al. Clinical manifestations of dermatomyositis and polymyositis in adults. https://www.uptodate.com/home. Accessed April 24, 2017.
- Chang-Miller A (expert opinion). Mayo Clinic, Rochester, Minn. May 10, 2017.