Most of our understanding about the afferent (sensory) neuronal pathways regulating the cough reflex comes from studies performed in animals. 5, 6 These contrasting functions and consequences of cough highlight the importance of balancing therapy-targeting cough, such that the defensive functions of the reflex are preserved, while limiting the role of cough in spreading harmful illnesses and adversely impacting patient sense of well-being. Furthermore, in diseases such as asthma, COPD, gastroesophageal reflux disease (GERD), and rhinosinusitis, cough may become excessive and harmful to the airway mucosa and adversely impact patient quality of life. However, cough is also a mechanism for the spread of life-threatening respiratory tract infections, including many forms of influenza, TB, severe acute respiratory syndrome, and Bordetella pertussis, the gram-negative bacteria responsible for whooping cough. 1, 2, 3, 4 Under normal conditions, therefore, cough serves an important protective role in the airways and lungs. An impaired cough reflex can have acute, dire consequences. The relevance of these neural systems to clinical phenomena, such as urge to cough and psychologic methods for treatment of dystussia, is high, and modern imaging methods have revealed potential neural substrates for some features of cough in the human.Ĭough preserves the gas-exchanging functions of the lung by facilitating clearance of aspirate, inhaled particulate matter, accumulated secretions, and irritants that are either inhaled or formed at sites of mucosal inflammation. The brainstem and higher brain control systems that process this sensory information are complex, but our current understanding of them is considerable and increasing.
The responsiveness and morphology of the airway vagal sensory nerve subtypes and the extrapulmonary sensory nerves that regulate coughing are described. Other bronchopulmonary sensory nerves, sensory nerves innervating other viscera, as well as somatosensory nerves innervating the chest wall, diaphragm, and abdominal musculature regulate cough patterning and cough sensitivity. These vagal sensory nerves terminate primarily in the larynx, trachea, carina, and large intrapulmonary bronchi. Bronchopulmonary C-fibers and a subset of mechanically sensitive, acid-sensitive myelinated sensory nerves play essential roles in regulating cough.
0 kommentar(er)
