A Rare Coexistence Of Asthma-COPD Overlap Syndrome and Obstructive Sleep Apnea With Restless Leg Syndrome and Thrombocytopenia: A Case Report

Abstract

Background: Overlap syndrome, defined by the coexistence of asthma-COPD overlap syndrome (ACOS) with obstructive sleep apnea (OSA), involves shared pathophysiological mechanisms including airway inflammation, systemic inflammation, and altered respiratory mechanics. Restless leg syndrome (RLS) is reported in 15–30% of patients with overlap syndrome, while thrombocytopenia remains a rarely documented association in this clinical context.

Case Presentation: A 63-year-old male presented with progressive dyspnea (mMRC grade 3) and nocturnal awakenings with tingling sensations and an irresistible urge to move his legs. He had poorly controlled persistent bronchial asthma with an ACT score of 9. Spirometry showed a pre-bronchodilator FEV1 of 50.5% predicted and FEV1/FVC of 54.4%, with minimal improvement following 2 µg salbutamol (FEV1 51.8%; FEV1/FVC 55.1%), confirming poor bronchodilator reversibility below both the 12% and 200 mL thresholds. High-resolution computed tomography confirmed centrilobular emphysema. Polysomnography demonstrated an apnea-hypopnea index of 29.3 events/hour with 137 hypopneas (19.8/hour), 65 apneas including one central apnea, and a nadir oxygen saturation of 78%, consistent with moderate-to-severe OSA. Serum IgE was elevated at 385.40 IU/mL and platelet count was 105,000/cmm. Autoimmune, infectious, and abdominal imaging workup were unremarkable. RLS was confirmed using all five IRLSSG diagnostic criteria.

Conclusion: This case highlights the rare coexistence of ACOS, OSA, RLS, and thrombocytopenia in a single patient. Chronic intermittent hypoxia and systemic inflammation appear to serve as central mechanistic links. Comprehensive multidisciplinary evaluation is essential in overlap syndrome, and further studies are needed to define the prevalence and pathophysiological basis of thrombocytopenia in this setting.