Inclusion Body Myositis

Inclusion Body Myositis (IBM) is an inflammatory muscle disease. It is characterized by slow and progressive muscle weakness and atrophy of the muscles. The disorder is very similar to another inflammatory myopathy called polymyositis. IBM is often diagnosed in cases of polymyositis that do not respond to therapy. But IBM has its own distinctive features.


The onset of muscle weakness in IBM takes place over months or years. IBM occurs more often in men than women. Symptoms usually begin after the age of 50. The disease can sometimes occur earlier. Falling and tripping are usually the first noticeable symptoms. For some patients the disorder begins with weakness in the hands. This can cause difficulty with gripping, pinching, and buttoning.

It affects muscles closest to the center of the body (proximal). It also affects muscles farthest (distal) from the center of the body. Other possible symptoms include:

  • Weakness of the wrist and finger muscles.

  • Atrophy of the muscles in the legs.

  • Atrophy or shrinking of the forearms.

  • Difficulty swallowing (dysphagia).


There is no standard course of treatment for IBM. Physical therapy may be helpful in maintaining mobility. Other therapy is symptomatic and supportive. IBM is generally resistant to all therapies. Its rate of progression also appears to be unaffected by treatment.