Polymyositis is an uncommon inflammatory disease, which can appear in combination with other illnesses and causes muscle weakness affecting both sides of the body. The muscle weakness associated with Polymyositis involves the muscles closest to the trunk, hips, thighs, shoulders, upper arms and neck. The weakness affects both the left and right sides of the body, and tends to gradually worsen. Polymyositis can make it difficult to climb stairs, rise from a seated position, lift objects or reach overhead.



Polymyositis signs and symptoms usually develop gradually, over weeks or months. The most common symptom is weakness of the muscles that results in varying degrees of loss of muscle power and atrophy. Patients can feel fatigue, a general feeling of discomfort, and have weight loss and low-grade fever. As for the visible symptoms on the skin, the eyes can be surrounded by a violet discoloration with swelling; there can be scaly reddish discoloration over the knuckles, elbows, knees, neck, and upper chest. Apart from that, this disease can lead to irregular heart rhythm, inflammation of the lungs with shortness of breath and even heart failure.



The exact cause of Polymyositis is still up to this date, but the disease shares many characteristics with the autoimmune disorders, in which the immune system mistakenly attacks the own body tissues.

Even though there are indicators of heredity susceptibility that can be found in some patients, there is indirect evidence of infection by a virus that has yet to be identified in a myositis, which is a muscle disease related to Polymyositis and that is particularly resistant to treatment. Aside from associated diseases, many other diseases and conditions can mimic Polymyositis. These include nerve-muscle diseases, metabolic disorders, hormone disorders, calcium and magnesium conditions and infectious diseases.


Risk Factors

Polymyositis most commonly affects adults from the age of 30 until the age of 50. It's more likely that a person from Afro-American ethnicity suffers from it, rather than a person from other ethnicity.



Possible complications of Polymyositis include:

  • Difficulty swallowing if the muscles in the esophagus are affected, which in turn may cause weight loss and malnutrition.
  • Aspiration pneumonia, which can lead to pneumonia.
  • If the chest muscles are affected by the disease, the patients can experience breathing problems, shortness of breath or, in severe cases, respiratory failure.
  • Calcium deposits in the late stages of the disease.



There is no prevention for Polymyositis. When the precise cause of Polymyositis is identified, preventative measures might be possible.