Cough-variant asthma: A diagnostic dilemma in the occupational setting

Abstract

Background: Cough-variant asthma (Corrao's syndrome) is defined as the presence of chronic non-productive cough in patients with bronchial hyperresponsiveness (BHR) and response to bronchodilator therapy. This variant of asthma may present a diagnostic problem in occupational medicine. Aims: To describe additional evaluation of cough-variant asthma in a cyanoacrylate-exposed worker in whom standard diagnostic testing was negative. Methods: A female beautician was evaluated for suspected occupational allergic rhinitis and asthma. A specific inhalation challenge test (SICT) was performed with cyanoacrylate glues used for applying artificial eyelashes and nails. Spirometry and peak expiratory flow (PEF) measurements were recorded hourly for 24h; methacholine challenge testing was performed and nasal lavage (NL) samples were analysed for eosinophilia. Results: After SICT, the patient developed sneezing, nasal airflow obstruction and cough. Declines in forced expiratory volume in 1 s and PEF were not observed. Eosinophil proportions in NL fluid increased markedly at 4 and 24h after SICT. A significant increase in BHR also occurred 24h after SICT. Conclusions: Clinical symptoms, post-challenge BHR and increased NL eosinophil counts confirmed a positive response to SICT and validated the diagnosis of cough-variant occupational asthma. SICT may be useful in cases where history and clinical data suggest cough-variant asthma and spirometric indices are negative.