The effect of altered head and tongue posture on upper airway volume based on a validated upper airway analysis-An MRI pilot study

Objective To determine the influence of altered head or tongue posture on upper airway (UA) volumes using MRI imaging based on a new objective and validated UA evaluation protocol. Setting and sample population One supine CBCT and five sagittal MRI scans were obtained from ten subjects in different head and tongue positions: (a) supine neutral head position (NHP) with the tongue in a natural resting position with the tip of the tongue in contact with the lingual aspect of the lower incisors (TRP); (b) head extension with TRP; (c) head flexion with TRP; (d) NHP with the tip of the tongue in contact with the posterior edge of the hard palate (THP); and (e) NHP with the tip of the tongue in contact with the floor of the mouth in contact with the caruncula sublingualis. Material and methods Based on a validated CBCT UA analysis, the retropalatal, oropharyngeal and the corresponding total volumes were measured from each MRI scan. Wilcoxon signed-rank test was applied to determine the statistically significant difference in mean volume between the baseline head and tongue posture (NHP with TRP) and the other postures. Results Five females and five males with a mean age of 46.5 +/- 13.7 years volunteered for this pilot study. UA volumes, particularly the oropharyngeal volume, increased significantly with head extension and NHP with THP and decreased significantly with head flexion. Conclusion Altered head and tongue posture proved to affect UA volumes, thus representing confounding variables during three-dimensional radiographic image acquisition.