Mechanisms of cough.

OBJECTIVE

To review recent developments in the mechanisms of chronic cough.

RESULTS

Although cough prevalence is similar across the world, there are significant regional differences in the diseases associated with cough. This may represent regional differences in diet, environmental exposure, and diagnostic assessment and labelling. Cough can be reliably measured using several validated questionnaires and objective tools that monitor cough frequency and cough reflex sensitivity. Cough with eosinophilic bronchitis responds to anti-inflammatory therapy with corticosteroids and montelukast. The absence of airway hyperresponsiveness may be because of the release of a bronchoprotective mediator, prostaglandin E2. Cough with neutrophilic bronchitis is associated with rhinitis and gastroesophageal reflux disease. Laryngeal hypersensitivity (LHS) is an important new concept that explains cough mechanisms, identifies potentially new pharmacotherapies that target neural pathways and also transient receptor channels, and demonstrates how behavioural therapies can be effective in refractory cough. The concept also explains symptoms in a variety of related syndromes such as vocal cord dysfunction.

CONCLUSIONS

New insights into cough mechanisms that focus on LHS help explain cough symptoms and the place of effective therapies including speech pathology intervention and neuromodulators.