Despite empiric treatment in the hospital with diuretics, antibiotics, and noninvasive positive-pressure ventilation, the patient’s dyspnea progressed. Based on his physical exam and the chest radio- graph demonstrating bilateral elevation of the hemidiaphragms, Neurology was consulted to evaluate for a neuromuscular etiology of dyspnea. Electromyogram of the finger flexors, quadriceps, and right hemidiaphragm showed reduced recruit- ment of muscle fibers and small motor unit potentials. The electromyogram was an abnormal study and demonstrated electrophysiological evidence of a proximal and distal myopathy, as well as fibrillation potentials suggestive of myonecrosis, fiber splitting, and vacuolization consistent with inclusion body myositis. Muscle biopsy of the left vastus medialis muscle revealed rimmed vacuoles in muscle fibers with necrosis, regeneration, and congophilic staining inclusions, consistent with a di- agnosis of inclusion body myositis (IBM) (Figures 1 and 2). Unfortunately, the patient developed worsening respiratory failure necessitating intubation and mechanical ventilation. In concordance with the patient’s wishes and advanced directives, ventilatory support was withdrawn. DISCUSSION Dyspnea is an extremely common complaint, particularly in the elderly. While the most common causes of dyspnea involve the respiratory and cardiovascular systems, it is essential to maintain a broad differential diagnosis, as there are a myriad of etiologies for dyspnea, spanning every organ system. Dyspnea reflects inadequate oxygen delivery to systemic organs, result- ing in a sensation of breathing discomfort. Inadequate respiratory drive and oxygen intake, impaired gas exchange, shunt physi- ology, reduced oxygen carrying capacity, inadequate pumping of the oxygen-rich blood, and poor oxygen exchange at periph-
Figure 1: Autoaggressive inflammatory exudate surrounding and invading muscle fibre (**) and vacuolated muscle fiber (*). Image courtesy of Dr. Andrew Engel.
Figure 2: Congophilic deposit in muscle fiber visualized with rhodamine fluorescence. Image courtesy of Dr. Andrew Engel.
Radiographs of the chest demonstrated no evidence of pulmonary edema or infectious pneumonia. Transthoracic echocardiogram showed no wall motion abnormalities, and left ventricular ejection fraction, as well as right ventricular systolic pressure, was unchanged from six months prior. Ventilation perfusion scan of the lungs was performed, which demonstrated lowprobability for chronic pulmonary embolism.
eral tissues may all contribute to the sensation of dyspnea. There are many neuromuscular conditions that may result in dyspnea. Guillain Barre Syndrome is a progressive inflammatory demyelinating polyneuropathy that often results in symmetric distal weakness and can progress to severe respiratory muscle weakness. Amyotrophic lateral sclerosis is a progressive, incurable neurodegenerative con- dition that causes combined upper- and lower-motor neuron
J La State Med Soc VOL 166 November/December 2014 255
Made with FlippingBook - Online catalogs