Variation in Maxillary Sinus Anatomy: Implications of Ostium Positioning on Health Disparities in Sinusitis
Authors: Kim Suhhyun , Butaric Lauren N. , Maddux Scott D. 
Published: April 2020

Over 30 million people are diagnosed with sinusitis annually, yet potential anatomical etiologies behind sinus infections remain poorly understood. Paranasal sinus drainage is mediated by mucociliary transport and gravity, but the human orthograde posture and superior positioning of the maxillary sinus (MS) ostia increase reliance on the mucociliary system. Moreover, previous research has suggested that regional differences in MS size and shape may contribute to disparities in sinusitis susceptibility. The purpose of this study was to examine overall MS size and shape, including MS ostium positioning, among three different ancestral groups, to assess potential impacts on drainage and infection risks. Employing CT scans (n=167) of crania from European, East Asian, and Equatorial African ancestries, we collected 28 3D coordinate landmarks per specimen. A total of 34 linear measurements of the MS and surrounding facial features were subsequently calculated and employed in multivariate analyses. MANOVA test results reveal significant differences between regional groups (Wilk’s λ = 0.807, p < 0.0001) and between the sexes (Wilk’s λ = 0.813, p < 0.0001), but no significant interaction between region and sex (Wilk’s λ = 0.971, p = 0.3223). ANOVA and Tukey‐Kramer test results indicate that Asians have both a significantly taller MS (F=15.4, p<0.0001) and a significantly greater distance from the MS floor to the ostium (F=13.5, p<0.0001) compared to Europeans and Africans. Further, a ratio of these two linear variables reveals that the MS floor‐to‐ostium distance constitutes a greater percentage of overall MS height in Asians (62%) than Europeans (60%) or Africans (59%). A canonical variate (CV) analysis of the 28 3D coordinate landmarks provides corroborative results, with CV1 accounting for 70.58% of total variance and separating Asians from Europeans and Africans. Morphologically, CV1 predominantly reflects a lower MS floor in Asians, while the relative superior‐inferior position of the MS ostium within the face appears similar across all ancestries. Cumulatively, these results suggest that both the taller sinus and greater MS floor‐to‐ostium distance in Asians are attributable to a more inferiorly positioned MS floor. As a greater distance from the MS floor to the ostium may lead to increased pressure on the mucociliary clearance, our results suggest that individuals of Asian ancestry may be at a greater risk for chronic sinusitis compared to those of European and African ancestries. Our study thus provides tentative evidence that there may be an anatomical etiology for chronic sinusitis despite an absence of anatomical defect. The increased risk for persistent inflammatory condition is also important since it has been accompanied with subsequent head and neck cancer diagnoses. Additional research into the prevalence of MS sinusitis in these populations is warranted to evaluate possible contributions to health disparities.Support or Funding InformationThis work is partially supported by a grant funded to Dr. Jamboor Vishwanatha by the Cancer Prevention and Research Institute of Texas (Award #: RP170301).