The drainage system of the paranasal sinuses: A review with possible implications for balloon catheter dilation

Background: Intersinus connections and accessory ostia of the maxillary sinus are well known to rhinologic surgeons but are less known for the remaining paranasal sinuses. Probing and dilatation of the natural ostia of diseased sinuses is being popularized currently by the clinical value of balloon catheter dilation (BCD). Although short-term high success rates with treatment of the dilated ostia/duct have been reported with this technique, the potential impact of fractures of adjacent bony septae on accessory sinus ostia, on mucosally lined surfaces, and on intersinus drainage pathways still has not been considered. The aim of this study was to review the literature on accessory sinus ostia, intersinus connections, and mucociliary drainage pathways for the entire sinus system that are relevant to BCD. Methods: A literature review was performed. Results: Accessory sinus ostia exist for each paranasal sinus. Many sinuses drain not only directly into the nasal cavity but also indirectly through adjacent sinuses. Of note, one major drainage pathway of the frontal sinus is over the ethmoid sinuses and via the ethmoids into the maxillary sinus and subsequently into the nose. Drainage of the sphenoid sinus exists both through posterior ethmoidal cells and directly into the nasopharynx. Conclusion: Accessory ostia are not only common for the maxillary sinus but also for the entire paranasal sinus system. BCD may potentially inadvertently impair mucociliary clearance of the sinuses through effects on secondary drainage pathways. (Am J Rhinol Allergy 25, 245-248, 2011; doi: 10.2500/ajra.2011.25.3647)