Synonyms
IBM

Disorder Subdivisions
Inflammatory Myopathy

General Discussion
Inclusion body myositis (IBM) is a rare inflammatory muscular disorder that usually becomes apparent during adulthood. The disorder presents as slow progressive weakness and withering away (atrophy) of the muscles (myositis), especially of the arms and legs. Inclusion body myositis frequently is diagnosed when a patient is unresponsive to therapy prescribed for polymyositis.

IBM is characterized by the gradual onset (over months or years) of muscle fatigue and weakness; a clear tendency to strike men more frequently than women; and affecting both the muscles closest to the body抯 trunk (proximal) and those farthest from the trunk (distal). Onset is usually after age 50, although it may occur earlier.