Spatial analysis of transnasal olfactory cleft access: a computed tomography study.

Objective: To our knowledge, the spatial access of naris to olfactory cleft has not been quantified. We aimed to study the relationship and space of middle turbinate, septum, anterior nasal spine and cribriform plate to improve topical medication delivery and drug applicators. Methods: One hundred CT scans of patients (50 males, 50 females) over the age of 18 were included. Subjects with radiographic sinonasal pathology, previous surgery, or specific variant nasal anatomy were excluded. Scans were independently reviewed and bilateral measurements on bony landmarks were taken by two blinded authors. Inter-rater reliability was analysed with intraclass correlation. Results: The average age was 46.26 years (σ = 14.0). Average distance from the anterior nasal spine to olfactory cleft was 52.3 mm (σ = 4.2 mm), and the average length of cribriform plate was 18.8 mm (σ = 3.8) with an angle relative to hard palate averaging -8.8 degrees below parallel (σ = 5.5 degree). The widths of the olfactory cleft at anterior and posterior edges of cribriform plate were 2.3 mm (σ = 0.7 mm) and 2.0 mm (σ = 0.7 mm). Conclusions: The findings suggest a 52.3 mm distance from the naris to the anterior border of cribriform plate. The average width along this path was 3.2 mm, suggesting devices narrower than this could potentiate direct drug delivery access.