Inclusion Body Myositis (IBM) is very similar to PM.  In fact, many doctors believe patients diagnosed with PM that do not respond to treatment may have IBM.  The only definitive test for IBM is a muscle biopsy.

Onset of muscle weakness in IBM is usually very gradual, taking place over months and years.  It is different from PM in that both proximal and distal muscles are affected.  Typical findings include weakness of the wrist flexors and finger flexors.  Atrophy, or shrinking, of the forearms is characteristic.  In the legs, Atrophy of the quadriceps muscle is common in varying degrees of weakness in other muscles. Difficulty swallowing (Dysphagia) occurs in about half the patients with IBM.  Some patients have no pain - others have a severe amount of pain.

Fine motor movements such as lifting any flat item - pencil, paper, etc. - from a desk or floor, buttoning a shirt, zipping pants, sewing, writing and even the ability to take care of personal hygiene or feed themselves as the disease progresses, encompasses the necessity of help in dressing, tying shoes, and even showering.  The use of a wheel chair or scooter for mobility becomes necessary after the canes and walkers aren't beneficial anymore.

Symptoms of IBM usually begin after age 50, although no age group has been entirely excluded.  IBM occurs more frequently in men than women.  About one in ten cases of IBM may be hereditary.

Unfortunately, there is no known treatment for individuals with IBM, but IVIg has shown some improvement in patients diagnosed very early.  Patients having IBM for a long time have nothing to benefit their condition.