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Abstract: Chronic cough remains a challenge to many clinicians because there is often no diagnostic link to causation, and because indirect antitussives are largely ineffective. Chronic cough can also be a predominant symptom associated with many chronic respiratory diseases such as COPD, asthma and pulmonary fibrosis. Chronic cough itself does impair the quality of life and is associated with psychological impairment. The symptoms associated with chronic cough include persistent tickling or irritating sensation in the chest or throat, hoarse voice, dysphonia or vocal cord dysfunction. Currently, the clinical diagnosis of cough is associated with chronic cough caused by airway eosinophilic conditions such as asthma, gastrooesophageal reflux disease or post-nasal drip (or upper airway syndrome), which implies cause and effect, or with chronic cough associated with other diseases such as COPD, cancer or heart failure, that does not necessarily imply cause and effect. A recently-recognised category is idiopathic cough, with no associated or causative diagnosis. We suggest that there is a better label needed for chronic cough, that includes the common association with a hypersensitive cough response to tussive stimuli such as capsaicin or citric acid. This would invoke a hypersensitive syndrome, and there are good reasons to use a new label that would encompass the problem of chronic cough: the chronic ‘cough hypersensitivity syndrome’. This would focus the problem on the cough symptomatology and lead to greater focus on understanding the mechanisms of cough sensitisation, with the ultimate aim of obtaining more effective antitussives. [Copyright &y& Elsevier]

Abstract: Cough is the most common complaint that leads patients to seek medical attention. Especially chronic persistent cough is annoying, and requires appropriate diagnosis and treatment. Recent cough guidelines and original papers on cough epidemiology from various countries show remarkable differences in the aetiology of chronic cough among countries, especially between US, UK and Japan. Entities associated with rhinosinus disease (post-nasal drip/upper airway cough syndrome reported from the US, rhinitis or rhinosinusitis from the UK, and sinobronchial syndrome from Japan), and eosinophilic lower airway disorders (cough variant asthma, non-asthmatic eosinophilic bronchitis and atopic cough) are most confusing and might involve significant overlap. In this article, issues related to chronic cough aetiology are discussed, including geographic issues, e.g. ‘simple’ geography or difference in race, and difference in patient characteristics possibly arising from difference in the medical system. [Copyright &y& Elsevier]

Abstract: Airway mucosal changes have been reported in chronic cough. In cough variant asthma and in eosinophilic bronchitis, there is evidence of eosinophil infiltration and sub-basement membrane thickening. In non-asthmatic cough, an increase of bronchoalveolar mast cells, mucosal mononuclear cells, and epithelial shedding have been reported. In a more recent study, evidence of airway wall remodelling has been observed in both asthmatic and non-asthmatic cough, such as an increase in sub-basement membrane thickness, goblet cell area, vascularity and vessel size. Smooth muscle area was increased in non-asthmatic coughers. Heightened cough sensitivity in non-asthmatic coughers was related to the degree of goblet cell hyperplasia and epithelial shedding. Cough reflex may be heightened by increased production of growth factors that might be further enhanced by the physical effects of cough on the airways. Mast cells may participate in the cough pathophysiology through release of growth factors as well as tussive mediators. Changes in the airway wall mucosa and epithelium may be important in the pathogenesis of cough receptor sensitization. [Copyright &y& Elsevier]

Abstract: Cough variant asthma and the closely related corticosteroid responsive cough syndromes eosinophilic bronchitis and atopic cough are common causes of chronic cough. The diagnosis is often not overt but detailed investigation of airway responsiveness and airway inflammation can be helpful. Cough variant asthma, eosinophilic bronchitis and atopic cough are all associated with eosinophilic airway inflammation, which is similar to that seen in non-cough predominant asthma. However, evidence of activated mast cells and increased concentrations of mast cell products appears to be confined to the conditions associated with cough, suggesting a role for mast cell degranulation in the superficial airway structures in the pathogenesis of cough. Cough variant asthma is typically corticosteroid responsive; leukotriene antagonists and antihistamines also help. Further study of this interesting asthma variant may increase our understanding of the relationship between airway inflammation and airway dysfunction. [Copyright &y& Elsevier]

Abstracts: Patients with chronic obstructive pulmonary disease (COPD) most commonly complain of cough, production of phlegm and breathlessness. The cough reflex sensitivity is heightened compared with that in healthy volunteers and is similar to that in subjects with asthma. The degree of airflow obstruction does not predict cough reflex sensitivity or objective cough counts, implying an independent process. Objective cough rates seem to be relatively low in COPD, despite frequent reporting of the symptom by patients. The relative contribution of cough to disability in COPD seems to be small, if assessed by subjective reporting. Effective treatments for cough in COPD have not yet been identified. Improved outcome measures of cough, a better understanding of the mechanisms underlying cough, and the importance of cough to patients is required to progress in this field. [Copyright &y& Elsevier]

Following the experience of asthma, characterised by the presence of bronchial hyper-responsiveness, the notion has been accepted that the chronic cough of disease occurs as a result of altered sensitivity of the afferent limb of the cough reflex. Methods for testing for the ‘threshold’ for eliciting the cough reflex have also been borrowed from asthma care. In the main aerosols are inhaled that contain the relevant stimulus.A number of factors influence the cough response to inhaled aerosols. The distribution of the inhaled aerosol is important as certain chemically sensitive receptors are distributed in different regions of the lungs. The larynx and central airways are important but so too are the peripheral airways. The degree of bronchodilatation is also important as airway narrowing can, itself, induce coughing in man.Asthma, oesophageal reflux and rhinitis patients experience increased coughing, that is associated with increased sensitivity to inhaled capsaicin. In syndromes of chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) increased sensitivity to coughing with capsaicin is common. This appears a specific effect of the pathogenic process of the disease. Modification of the disease process can lessen coughing and the sensitivity to capsaicin. [Copyright &y& Elsevier]