3D analysis of upper airway morphology related to obstructive sleep apnea severity

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder characterized by repetitive collapse of the upper airway during sleep. However, little evidence is available on the differences between the sub-regions of the upper airway morphology and OSA severity. Since orthodontists frequently perform cone beam computed tomography (CBCT) in the neck area, we aimed to investigate the relationship and the differences between upper airway morphology and OSA severity using CBCT.

The medical records, CBCT imaging of 21 OSA patients diagnosed by polysomnography, and the apnea-hypopnea index (AHI) results were included to classify OSA severity as mild, moderate, or severe. The minimum cross-sectional areas (MCA) and volumes of the upper pharyngeal airway boundaries in four sub-regions: nasopharynx, retropalatal, retroglossal, and hypopharynx were measured. Dolphin Imaging software was used for upper airway segmentation. The correlation coefficient (r), one-way ANOVA, and the least significant difference post hoc multiple comparison test were applied to fulfill the objectives.

A statistically significant relationship was found between the MCA of the nasopharynx and the AHI (r = -0.473, P < 0.05). Furthermore, a difference was found between mild and moderate and moderate and severe OSA severity in the MCA results of the retroglossal region (P < 0.05). However, no relationship was found between the upper airway volume and OSA severity.

MCA was moderately negatively correlated to AHI only in the nasopharynx subregion. Moderate OSA presented significantly less MCA than mild and severe OSA only in the oropharynx and retroglossal subregions.