Inferior Turbinate/Nasal Cavity Ratio: A Novel Objective Tool with Potential Clinical Implications

Abstract

Background: The nasal cavity is the upper part of the respiratory tract which communicates with the external environment through the anterior apertures. It also communicates with the nares, and the nasopharynx via the posterior apertures. The nasal cavity is divided into two by a septum, each cavity consisting of a roof, floor, medial wall, and lateral wall. The nasal cavity is formed laterally by the inferior, middle and superior nasal conchae (turbinates). Aim: The aim of the study was to investigate the dimensions of the inferior turbinate as seen in selected Nigeria subjects and develop novel anatomical parameters and indices with potential clinical implications. Methods: This retrospective study was done in the Radiology department of the Rivers State University Teaching Hospital following ethical approval, 339 CT films of adults (males and females) were analysed in this study. Sex and side differences were analysed using t-test, while relationship between anatomical structures were analysed using the Chi square test. The confidence interval was set at 95% and p < 0.05 was considered significant. The volume of the inferior turbinate and nasal cavity were measure and the inferior turbinate/nasal cavity ratio was calculated. Results: The mean volume of the inferior turbinate for males was 2.01±0.12, female was 2.22±0.14 and for the entire population it was 2.12±0.13. The mean volume of the nasal cavity for male and female were 15.98±0.40 cm3 and 14.73±0.34 cm3, respectively, whereas the average for the population was 15.35±0.37 cm3. Conclusion: To the best of our knowledge, this is the first research that used well defined anatomical landmarks in estimating the volume of the nasal cavity and inferior turbinate. This study also provided a clinically objective tool in assessing the degree of nasal cavity obstruction by providing a grading system for the inferior turbinate/nasal cavity. This tool will particularly be very useful in resource poor settings like ours where nasal endoscopy and rhinometry may not be readily available and affordable. Therefore radiologist can use this grading system to grade the degree of inferior turbinate hypertrophy and predict the degree of nasal obstruction and severity of symptoms.