Polymyositis (PM) is one of the inflammatory myopathies, a group of muscle diseases that involve inflammation of the muscles or associated tissues, such as the blood vessels that supply the muscles
. The condition is thought to be an autoimmune disease, where the immune system mistakenly attacks the body's own tissues
. Polymyositis usually affects adults in their 30s, 40s, or 50s, and women are affected more often than men
. The symptoms of polymyositis include:
- Muscle pain and stiffness
- Muscle weakness, particularly in the abdomen, shoulders, upper arms, and hips
- Joint pain and stiffness
- Trouble catching your breath
- Problems with swallowing
- Irregular heart rhythms, if the heart muscle becomes inflamed (myocarditis)
The exact cause of polymyositis is unknown, but it shares many characteristics with autoimmune disorders
. In some cases, the condition may be triggered by a virus or an autoimmune reaction
. Risk factors for polymyositis include having lupus, rheumatoid arthritis, scleroderma, or Sjogren's syndrome
. Polymyositis can lead to great discomfort, but effective treatments are available, and the condition is not generally life-threatening
. Physical therapy is an important component of treatment
. In some cases, the disease may be present in combination with other illnesses, such as cancer
