Inclusion Body Myositis

Inclusion body myositis (IBM) is an inflammatory muscle disease characterized by slow and relentlessly progressive muscle weakness and atrophy of the muscles.

The disorder is very similar to another inflammatory myopathy called polymyositis. In fact, IBM is often diagnosed in cases of polymyositis that are unresponsive to therapy. However, IBM has its own distinctive features. The onset of muscle weakness in IBM is generally gradual (over months or years). Also, IBM, which occurs more frequently in men than women, affects both the proximal (closest to the center of the body) and distal (farthest from the center of the body) muscles. There may be weakness of the wrist and finger muscles and atrophy of the quadricep muscles in the legs. Atrophy or shrinking of the forearms is also characteristic. Difficulty swallowing (dysphagia) occurs in approximately half of IBM cases. Symptoms of the disease usually begin after the age of 50, although the disease can occur in any age group. Falling and tripping are usually the first noticeable symptoms of IBM. For some patients the disorder begins with weakness in the hands causing difficulty with gripping, pinching, and buttoning.

There is no standard course of treatment for IBM. The disease is unresponsive to corticosteroids and other immunosuppressive drugs. Some evidence suggests that intravenous immunoglobulin may have a slight beneficial effect in a number of cases. Physical therapy may be helpful in maintaining mobility. Other therapy is symptomatic and supportive.

IBM is generally resistant to all therapies, and its rate of progression also appears to be unaffected by the present treatments.

Information provided by the
National Institute of Neurological Disorders and Stroke,
National Institutes of Health

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.