A 63-year-old Caucasian male is being evaluated for difficulty sleeping and morning headaches. He has been sleeping upright for the last two months because he gets short of breath while lying flat. He has also had mild dysphagia and difficulty walking for the last six months. He denies any chest pain, palpitations, wheezing, cough, or lower extremity swelling. His blood pressure is 127/86 mmHg and heart rate is 96/min, regular in rhythm. His BMI is 27 kg/m². Physical examination reveals some lower extremity muscle atrophy and tongue fasciculations. There are minimal crackles at the right lung base. His forced vital capacity is 57% of the predicted value while upright and 42% of the predicted value while supine. Which of the following is the most likely cause of this patient's dyspnea?

Question

Quizplus · Accepted Answer

Explanation: The clues to diagnosing this patient's pulmonary complaints are his lower extremity muscle atrophy and tongue fasciculations, which both represent lower motor neuron signs and are suggestive of a neurologic disease such as amyotrophic lateral sclerosis (ALS), although further evaluation would be required to make this diagnosis. His complaints of dysphagia and difficulty walking are likely secondary to neurologic disease as well. As a result of these findings, the most likely cause of this patient's complaints is diaphragmatic paralysis. Patients with diaphragmatic paralysis typically present with shortness of breath that is worse in the supine position, and as a result, it is easy to see how this symptom can erroneously lead to a cardiac workup. This patient's ventilatory function is measurably worsened when lying supine as shown by his decrease in forced vital capacity. This difficulty with lying supine can lead to poor sleep, daytime fatigue, and morning headaches. Pulmonary auscultation is typically nonspecific, but findings of atelectasis in the lower lobes can occur. One helpful clue on physical examination suggestive of diaphragmatic paralysis is paradoxical abdominal wall retraction during inspiration when the patient is lying supine, which occurs because the diaphragm is not contracting. A sniff test using fluoroscopy can be helpful in confirming the diagnosis. (Choice A) Patients with obstructive sleep apnea often have complaints of difficulty sleeping and headaches. However, this patient's neurologic findings are more suggestive of diaphragmatic paralysis. (Choice B) This patient's problems with dysphagia could potentially lead to aspiration. However, aspiration generally only occurs sporadically and it is clear that this patient becomes short of breath immediately upon lying supine. (Choice C) Dilated cardiomyopathy can lead to congestive heart failure with resulting orthopnea similar to that seen in this patient. However, this patient's neurologic findings point more towards diaphragmatic paralysis. (Choice E)The dyspnea of interstitial lung disease does not generally worsen when lying supine. In addition, this patient's neurologic symptoms suggest the correct diagnosis of diaphragmatic paralysis. Educational objective: Diaphragmatic paralysis can lead to orthopnea, which can be easily confused with congestive heart failure. The most common causes of bilateral diaphragmatic paralysis are neurologic diseases such as ALS. Therefore, in patients with this presumed diagnosis, the presence of neurologic signs and symptoms should be sought elsewhere in the body.

A 63-Year-Old Caucasian Male Is Being Evaluated for Difficulty Sleeping