Relationships among Retropalatal Airway, Pharyngeal Length, and Craniofacial Structures Determined By Magnetic Resonance Imaging in Patients with Obstructive Sleep Apnea

Abstract

BackgroundThe integration of anatomical and nonanatomical parameters will improve our ability to predict the outcomes of OSA treatment. Currently, no standardized, quantitative classification of upper airway anatomical traits is available. The retropalatal (RP) airway is the most important area to consider when planning anatomical treatment. However, current evaluation methods feature qualitative conventional endoscopy. Here, we describe a quantitative magnetic resonance imaging (MRI) method used to classify RP airway patterns.MethodsWe recruited 117 males; 20 simple snorers and 97 patients with OSA. Lateral/anteroposterior ratios were calculated in three parallel planes and RP patterns were classified accordingly. Lateral wall soft tissue structures, skeletal dimensions representing those planes, pharyngeal lengths, and skeletal and vertical axis ratios were also measured.ResultsBoth the cross-sectional area at the hard palate level and the RP lateral dimension were associated with OSA. OSA patients had longer pharynges than controls. The oblique pattern was associated with narrow lateral dimensions. The vertical pattern was associated with a narrow nasopharynx but a longer pharynx. The airway ratio at the hard palate level and the skeletal ratios of all three planes were negatively correlated with the vertical axis ratio and together explained 40.8% of the variance in the vertical axis ratio.ConclusionsThe data suggest that anatomical imbalances between the craniofacial skeletal and soft tissue structures affect pharyngeal airway morphology in all three dimensions. The dimensions of the nasopharynx, the cross-sectional area at the hard palate level, and pharyngeal length were associated not only with the RP patterns but also with OSA severity. This study affords insights into upper airway anatomy and RP patterns and may help diagnose OSA patients and aid in the selection of an appropriate therapy.