Nasal airway in obstructive sleep apnea: a supine magnetic resonance imaging study

Obstructive sleep apnea (OSA) is characterized by recurrent collapses of the upper airway during sleep. Although nasal obstruction has been identified as an independent risk factor for OSA and extensively studied, the relationship between nasal anatomical structures and OSA remains poorly understood. The objective of this study was to determine the relationship between the nasal cross-sectional area (CSA), as measured by magnetic resonance imaging in the supine position, and the presence of OSA, as well as to investigate its correlation with OSA severity.

In this cross-sectional study, a total of 111 participants were enrolled, comprising 88 patients with OSA and 23 healthy controls. All participants underwent polysomnography to determine their apnea-hypopnea index (AHI). Subsequently, MRI scans were performed in the supine position to measure CSA at distances of 1.5, 2, 2.5, 3, 4, 5, and 6 cm posterior to the most anterior point of the nasal cavity. Participants were stratified into groups based on AHI severity, and statistical analyses were conducted to determine the correlation between CSA measurements and the AHI.

Significant intergroup differences were observed in the minimum CSA at the 2.5 and 4.0 cm levels. No difference was found in the sum of nasal CSA at any level. Furthermore, no group differences were found in either nasal cavity volume or surface area. A comparison between healthy individuals and OSA patients revealed that advanced age, a higher body mass index, male sex, and a reduced total minimum nasal cross-sectional area (TMCA) were independent and significant predictors of OSA.

TMCA was identified as a predisposing factor for OSA, but it was not found to be associated with the severity of the condition. Furthermore, long-term, severe OSA may contribute to an enlargement of the CSA.