Respiratory muscle weakness and diaphragmatic failure is a rare presentation of hypercortisolism. We report a case of Cushings syndrome in a 60-year-old female with history of rheumatoid arthritis, biliary cirrhosis and hypothyroidism. She presented to the Respiratory Physicians with progressive worsening of shortness of breath. Clinical assessment excluded infective pathology, cardiac failure or asthma. Pulmonary function tests (PFT) showed restrictive defect and reduced transfer factor, but high-resolution computer tomography scan did not show pulmonary fibrosis. Sequential chest X-rays/CT and PFT were unable to ascertain the diagnosis despite worsening dyspnoea. Lung biopsy showed non-specific changes and she was considered for lung transplantation. During this period the patient required ITU admission for severe respiratory failure secondary to pneumonia. During this admission, ultrasonography (USG) noted severe reduction in diaphragmatic movement. Respiratory muscle tests confirmed global respiratory muscle and diaphragmatic weakness. Electromyography and nerve conduction study were normal and investigations for myasthenia were negative.
During the post-discharge follow-up, she was noted to have features of Cushings syndrome, disproportionate to the previous use of steroids, and she was referred to our clinic. In addition to the typical facial and truncal appearance she had worsening hypertension and significant weight gain. Urinary cortisol ranged between 250 and 500 nmol/24 hr, post-dexamethasone cortisol was 477 nmol/l and ACTH <5 ng/L confirming the diagnosis of ACTH-independent Cushings syndrome. Abdominal CT scan showed 2.6 cm enhancing mass in the left adrenal. Following successful adrenalectomy her symptoms and objective parameters of respiratory function, respiratory muscle strength and diaphragmatic movement demonstrated significant improvement.
Only few cases have been reported respiratory muscle weakness sufficient to cause significant respiratory insufficiency in patients with Cushings syndrome. However, unlike our patient none of them had diaphragmatic failure. This case highlights the need to consider this unusual manifestation of Cushings syndrome in an appropriate context.