Idiopathic bilateral diaphragmatic dysfunction as a cause of dyspnea

Diaphragmatic paralysis is an unusual and often underrecognized cause of dyspnea. We present a case of bilateral diaphragmatic paralysis with no identifiable etiology. Our patient is a 73-year-old female with a history of smoking who presented with dyspnea and orthopnea. She was treated for obstructive lung disease with no improvement in dyspnea despite adequate therapy. She had pulmonary function tests (PFTs) that revealed marked decrease in vital capacity and was unable to perform lung volume maneuvers supine due to marked dyspnea. The maximal inspiratory pressure was 37 in the upright position and decreased to 27 in the supine position. She was given a presumptive diagnosis of idiopathic bilateral diaphragmatic dysfunction. Given the history, physical exam, and PFT findings, we felt that the patient did not need further invasive testing. The patient was treated with noninvasive mechanical ventilation due to hypercapnia and her symptoms improved.