April 20, 2015: Inclusion Body Myositis

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April 20, 2015

Inclusion Body Myositis

The idiopathic inflammatory myopathies include polymyositis, dermatomyositis and inclusion body myositis. Inclusion body myositis is now felt to represent upwards of one quarter of the cases of the inflammatory myopathies. Most commonly, IMB affects men more than woman and its onset is frequently around the sixth decade. As the nature of the disease is often an insidious onset, many patients with IBM often go undiagnosed for years. First symptoms include issues with lower extremity weakness such as going up stairs, which progresses to involve the upper extremities, more commonly the distal flexor muscle groups. As the disease progresses, patients may lose the dexterity of the fingers and fine motor movements making buttoning a shirt difficult. Dysphagia and oropharyngeal weakness is possible as the disease progress, given the involvement of the cricopharyngeal muscle groups. A diagnosis of IBM can sometimes be made immediately upon evaluation of a patient. Frequently, there is atrophy of the flexor forearm and extensor leg compartment. On greeting the patient, a weak handshake is noted as patients are unable to flex the long flexor muscle groups.


  1. Amato AA and Greenberg SA. Inflammatory Myopathies. Continuum (Muscle Disease) December 2013: 1615-1633.

Submitted by James Addington, M.D. Resident Physician, Department of Neurology, University of Virginia

Disclosures: Dr. Addington is a member of the Residents & Fellows Section of Neurology.

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