Anatomic description of the middle meatus and classification of the hiatus semilunaris into five types based upon morphological characteristics

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. Ninety seven 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 for the openings of the paranasal sinuses and the morphology of the hiatus semilunaris. The average widths for the middle meatus were 1.69-mm anteriorly, 2.83 mm at the transition angle, and 4.74-mm posteriorly. The posterior width was significantly larger than either of the two other measurements. The length of the hiatus semilunaris was found to be shorter on both left-sides and in females. The hiatus semilunaris was categorized into five types 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. Knowing the discrepancy of hiatus semilunaris lengths between right and left sides and males versus females may guide advancement of endoscopic instruments into the nasal cavity. Describing the five distinct types of the hiatus semilunaris allows the distinction of normal variation in this anatomic space versus pathologic condition.

Anterior meatuscopy is more reliable than a sniff test for predicting nasal patency before transnasal endoscopy

“…Given that a sniff test is not only unreliable but also cannot be performed in patients who are unable to sniff, anterior meatuscopy is an attractive alternative. Using anterior meatuscopy, we revealed that the anterior INM is broader than the posterior INM, whereas the anterior MNM is narrower than the posterior MNM; these endoscopic observations are compatible with a cadaveric anatomical study 19 . We have also found that the anterior CNM is narrower than the posterior CNM, which is also consistent with an anatomical study demonstrating that the INT bone is thicker anteriorly than posteriorly 20 .…”

Phase 1 clinical study to assess the safety of a novel drug delivery system providing long‐term topical steroid therapy for chronic rhinosinusitis

“…Treatment of presurgical CRS patients with a local drug delivery system requires a small‐profile product that can fit into the tight anatomy of an unoperated patient without obstructing air flow. The average width of a middle meatus is reported to be 1.69 mm anteriorly, 2.83 mm at the transition angle, and 4.74 mm posteriorly . The LYR‐210 depot is a miniaturized local drug delivery system designed to fit within, and conform to, the confined space of a patient's middle meatus.…”

Endoscopic meatus scoring scale versus sniff test to predict insertability before transnasal endoscopy: A prospective, randomized study

“…We have proposed a simple EMSS by anterior meatuscopy to select a meatus insertion tract for nasal anesthesia. In the anterior nasal cavity, the widths of the posterior meatuses, which are usually narrower than their anterior counterparts, are important . Other factors such as septum deviation or bony projection, mucosal or bony hypertrophy of the nasal turbinates, and the nasal cycle can also influence meatus patency.…”