Primary respiratory failure in inclusion body myositis.

The idiopathic inflammatory myopathies are a group of disorders characterized by acquired muscle weakness and presence of inflammatory infiltrates in skeletal muscle.1,2⇓ The three most common diseases within this group are dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM). Respiratory muscle weakness with respiratory failure is a well-recognized complication in PM and DM but has only rarely been reported in IBM.3,4⇓ Symptomatic respiratory failure in IBM is considered to be secondary to coincidental pulmonary disease.5 We report a patient with IBM who developed subacute respiratory failure caused by primary respiratory muscle weakness. A 58-year-old woman sought treatment for slowly progressive muscle weakness, dysphagia, and weight loss. Her medical history was unremarkable, and she did not use any myotoxic drugs. Physical examination revealed normal speech, mild facial weakness, dysphagia without aspiration, and generalized muscle weakness (Medical Research Council [MRC] score, 4) with asymmetric weakness of the forearm muscles (right, MRC 4; left, MRC 3). …