Characterizations of the Middle Meatus and Hiatus Semilunaris for the purposes of Endoscopic Procedures

Abstract

Anatomical variation of the lateral nasal wall, including the pathway from the frontal, ethmoidal and maxillary sinuses may affect the communication between the paranasal sinuses and the nasal cavity. The middle meatus and hiatus semilunaris are areas where variations can occur which predispose patients to recurring sinusitis. Endoscopy allows for visualization of the entire nasal cavity, for both diagnostic and therapeutic uses. The purpose of this study was to provide an accurate characterization of the middle meatus and hiatus semilunaris for the purposes of endoscopic procedures. 116 cadaveric lateral nasal walls were observed. The middle meatus was measured at three distinct points. Cranial length was also recorded. A 3D digitizer was used to record spatial relationships between the openings of the paranasal sinuses and the hiatus semilunaris. The average widths for the middle meatus were 1.69mm anteriorly, 2.83mm at the transition angle and 4.74mm posteriorly. The posterior width was significantly larger than either of the two other measurements. The hiatus semilunaris was categorized according to the varying morphologies. Given that the middle meatus was significantly wider posteriorly, our findings support the recommendation that entering the middle meatus posteriorly may allow an endoscopic surgeon easier access to the structures of the lateral nasal wall.