General Medical Information

The Ostiomeatal Complex

Ronald G. Amedee
Andrew J. Miller

The anterior ethmoidal cells reside at a point in the ethmoidal infundibulum where common drainage exists between these cells and the frontal and maxillary sinuses. Many processes can block the anterior ethmoidal cells, including those affecting ciliary motion such as temperature less than 18°C, an excessively acidic or basic environment, or primary ciliary abnormalities such as dynein arm defects. Production of an inadequate mucous blanket, such as with dehydration or humidity less than 50%, causes sinus obstruction because the periciliary layer becomes too thin to allow normal movement of the cilia. Immunoglobulin deficiency in the mucus decreases infection-fighting capability and can allow viruses to invade the mucosa, and the viruses directly decrease ciliary motion.

When the mucosa of the paranasal sinuses becomes swollen and inflamed by any of the aforementioned mechanisms, two opposing mucosal layers often come into direct contact. Messerklinger found that the touching of these mucosal surfaces disrupts mucociliary clearance. These areas of direct mucosal contact are most likely to be present in the narrow channels of the ethmoidal infundibulum and ethmoidal cell system. Any event that occludes the anterior ethmoidal cells can cause mucosal inflammation sufficient to occlude the maxillary or frontal sinuses or can allow spread of infection to the maxillary or frontal sinuses from the ethmoidal infundibulum. This specific relation between the anterior ethmoidal cells and ethmoidal infundibulum complex in the pathogenesis of frontal and maxillary sinus disease led to the description of the area known as the ostiomeatal complex. Evidence now clearly exists that severe sinus disease in the maxillary and frontal sinuses resolves when normal aeration and mucociliary clearance are restored to the anterior ethmoidal cells.