Cough is a physiological response to mechanical and chemical stimuli due to irritation of cough receptors located mainly in the epithelium of the upper and lower respiratory tracts, pericardium, esophagus, diaphragm, and stomach. A complex reflex arc through the vagus, phrenic, and spinal motor nerves to the expiratory musculature generates an inspiratory and forced expiratory effort to clear the airways [1]. Under pathological conditions of known and unknown etiologies, chronic refractory cough (CRC) may become a major medical problem because patients may need to undergo repeated examinations before reaching a diagnosis, and/or try several treatments with sometimes poor symptom control, worsening their quality of life and increasing economic burden.
