Nitric oxide unravels the enigmatic function of the paranasal sinuses: a review of literature

Abstract

Abstract Background The physiological functions of the paranasal sinuses are as yet unclear, and it is often assumed that these empty air-filled spaces have no vital function in our body. Recently, nitric oxide has been reported to be synthetized in high concentration by the paranasal sinuses which seems to be the main function of these air-filled empty spaces. Body of abstract The functional role of the paranasal sinuses is still ambiguous despite the several hypotheses that have been put forward to justify their existence. Although it has been recently demonstrated that the paranasal sinuses produce large amounts of nitric oxide (NO), otolaryngologists overwhelmed by attempting to unravel the enigmatic etiology underlying chronic rhinosinusitis have interpreted the high NO output in this context. Nevertheless, NO prime function is vasodilation and has long been recognized to be produced by the endothelial cells. In this review, evidence in the literature is piled and pieces of the puzzle are put together to show that NO synthesized in the paranasal sinuses functions as an airborne messenger that induces pulmonary vasodilation and thereby decreases the workload on the heart. Recognition that the paranasal sinuses are in fact an organ with known function is likely to foster further research and has an impact on our current surgical philosophy. Conclusion The paranasal sinuses seem to play a vital physiological role in our body rather than being evolutionary remnants as initially thought. They are likely responsible for regulating the pulmonary blood pressure thereby preventing pulmonary hypertension.