Asthma and sinusitis.

Important relationships exist between the upper and lower airways. It is well known that sinusitis and asthma coexist in many patients, and evidence is accumulating that there may be a cause-and-effect relationship, that is, that sinusitis is an important trigger for asthma. Studies in children and adults indicate that appropriate medical and/or surgical therapy of sinusitis frequently leads to improvement in the asthmatic state. Possible mechanisms for this relationship include the eosinophil acting as an effector cell, inflammatory mediators, and a vagal reflex. Further investigations need to examine both prospective studies of the effect of medical therapy for sinusitis on asthma and basic mechanisms relating the upper and lower airways.