Author
Richard H. Zou, MD 1, Stephanie I. Maximous, MD, MS 1
1 Division of Pulmonary, Allergy, and Critical Care
Medicine, Department of Medicine, University of Pittsburgh Medical
Center, Pittsburgh, PA
Case
A 69-year-old woman with a history of cervical stenosis with recent anterior cervical discectomy and fusion and lumbar radiculopathy with foot drop presented with one year of generalized fatigue, lower extremity weakness, frequent falls, and unintentional 40 lb weight loss. These symptoms were accompanied by progressive exertional dyspnea; outpatient spirometry was notable for FEV1/FVC 0.87, FEV1 1.20 L (72% predicted), and FVC 1.38 L (62% predicted); no lung volumes were performed. The patient was admitted for failure to thrive. Physical examination was remarkable for tongue fasciculations, hyperactive jaw jerk, hand muscle atrophy, positive Hoffman’s sign, and preserved lower extremity strength. Her hospital course was complicated by nocturnal hypoxia requiring 3 L/min oxygen. Arterial blood gas, on room air, was notable for pH 7.34, pCO2 72 mmHg, pO2 49 mmHg, and HCO3 37 mEq/L. Review of prior chest radiography revealed persistently elevated left hemidiaphragm. The following test was subsequently performed:
Question
What is the most likely etiology of the patient’s mixed hypoxemic/hypercapnic respiratory failure?
A. Amyotrophic lateral sclerosis
B. Multiple sclerosis
C. Spinal stenosis
D. Iatrogenic phrenic nerve injury
E. Chest wall disorder
