Physiologie des sinus paranasaux

Paranasal sinuses are air-filled cavities which develop in facial and cranial bones. They are lined by a pseudo-stratified columnar ciliated respiratory epithelium. They are in connexion with the nasal fossa by the “ostium”, that is an obliged passage for the air and the point of convergence of all the ways of drainage. Permeability of the ostium is essential for good functioning of the sinuses. Persistent ostial obstruction leads to great changes in the partial pressures of the gazes (O2 and CO2) inside the sinus. The ciliary beat frequency decreases; the secretions stagnate and a proliferation of the bacteria occurs. Mucociliary clearance is the second component of the sinus physiology. It depends on the morphology and the quality of the cilia and on the rheologic properties of the mucus that lubricates and protects the underlying epithelium. Primary and secondary cilia dyskinesia and cystic fibrosis are typical conditions associated with impairment of the mucociliary clearance.