Chronic cough: new perspectives in its diagnosis and treatment.

At the recent 2011 ERS congress in Amsterdam, the founding meeting took place of the ERS Task Force on the “Diagnosis and classification of chronic cough – Consensus Document”. Briefly, two objectives were defined: one, to consolidate the new concept of chronic cough hypersensitivity syndrome; and two, the need to group within this syndrome all those entities associated with chronic cough, as a similar clinical history can be observed among them and there is a common physiopathological base, which is the reduced threshold of the cough reflex linked to the vagus nerve. The majority of the cough episodes are acute, but in some nonsmoker individuals who do not have chronic airflow obstruction andwhoarenot takingACE inhibitors and in thosewhompathological thoracic radiography has been ruled out, the cough can persist for more than 8 weeks, becoming an uncomfortable and distressing problem. Types of triggers have been identified for the cough reflex, thesebeing thermal, chemical andmechanical, andeven limited stimuli, such as changes in temperature, strong perfume or singing, lengthy speech or laughing can cause coughing crises. Up to two-thirds of patients with chronic cough admit to having these triggers1 and, furthermore, they frequently report other symptoms such as the “urgent need to cough”, the sensation of itchiness in the throat, sudden breathlessness and occasionally chest pain or dyspnea. When a chronic cougher presents with this group of triggers and symptoms, he/she is currently considered affected by the chronic cough hypersensitivity syndrome. Within this syndrome various phenotypes are differentiated. Up until a few years ago, three were recognized: eosinophilic inflammation of the airway, gastroesophageal reflux (GERD)and that linked to rhinitis-sinusitis. Recently, otorhinolaryngologists have defined another phenotype associated with laryngeal neuropathy.2 This “unifying” concept, with a common connection of chronic cough and innervation of the vagus, has lead to contemplating the respiratory tract together with the upper digestive tract and the larynx as one “physiological unit”, with the anatomical correlation in the forked axis that connects the stomach and the lungs through the laryngopharynx. A priori, any event that reduces the reflex threshold in those organswhere there are vagus receptors can trigger coughing crises. For instance, bronchospasm, acidification of the esophagus or the inflammation of the upper respiratory tract are known associations of chronic cough. Considered one by one, however, none of them alone evokes the start of the cough reflex3; therefore, it is now assumed that for chronic cough to start up and continue, it is necessary for there to be integration among different afferent pathways