• Yonglin Mai, Chen Zhan, Shengfang Zhang, Jiaxing Liu, Wanqin Liang, Jiawei Cai, Kefang Lai, Nanshan Zhong, and Ruchong Chen.
• State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China; Nanshan School of Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China.
• Chest. 2020 Jul 1; 158 (1): 264-271.

BackgroundA higher incidence of Arnold nerve reflex (ANR) has been observed in patients with chronic cough. However, the different ANR response in various causes of chronic cough remains unclear. Furthermore, it is unknown whether ANR will change after effective treatment.MethodsPatients with chronic cough were enrolled in the Guangzhou Institute of Respiratory Health. The causes of chronic cough were diagnosed via a validated management algorithm. Patients underwent an assessment of ANR response before and after 1 month of etiologic treatment.ResultsA total of 127 patients with chronic cough and 55 healthy control subjects were enrolled. The positive response, defined as cough-only ANR or urge-to-cough (UTC), was present in 14.8% of patients with cough variant asthma (CVA), 11.1% of patients with upper airway cough syndrome, 15.4% of patients with gastroesophageal reflex related cough (GERC), 4.8% of patients with eosinophilic bronchitis, and 26.9% of patients with unexplained cough (UC). No ANR or UTC was found in the healthy control subjects. The incidence of the positive response was higher in subjects with CVA, GERC, and UC compared with healthy control subjects (all P < .05). No difference was observed among the different causes of chronic cough (all P > .05). After 1 month of treatment, 87.5% of patients identified with a positive response changed to a negative response. In a subgroup analysis, an increased cough sensitivity to capsaicin was found in the patients with a positive response compared with the patients with a negative response (P < .05).ConclusionsA positive ANR appears to be a sign of vagal hypersensitivity and can be reversed after effective treatment of chronic cough. However, although various causes of chronic cough share a similar feature of an elevated ANR response in a minority of patients, there appears to be limited usefulness in assessing ANR because it does not appear to be a valid predictor of etiology of chronic cough or outcome of treatment.Copyright © 2020 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

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