Cephalometric comparison of pharyngeal changes in subjects with upper airway resistance syndrome or obstructive sleep apnoea in upright and supine positions.

The aim of the present study was to cephalometrically compare pharyngeal changes between upright and supine positions in patients with upper airway resistance syndrome (UARS) or obstructive sleep apnoea (OSA). Eighty-two OSA patients, 70 men (mean age 49 +/- 11.8 years) and 12 women (45.9 +/- 8.3 years), underwent cephalometric sleep apnoea analysis. One upright and one supine radiograph were taken of each patient (a total of 164 cephalometric radiographs). The results showed no significant changes either in naso- or hypopharyngeal soft tissues between the two positions. In contrast, the shortest distance from the soft palate (ve1-ve2) and the tip of the soft palate (u1-u2) to the posterior oropharyngeal wall was significantly narrower (P < 0.001) in the supine position. Furthermore, in the supine position a slight thickening in the soft palate (sp1-sp2, P < 0.05) was detected with no change in the length of the soft palate (PNS-u1). The form of the tongue changed significantly: it was shorter (Tt-Tgo, P < 0.001; Tt-va, P < 0.001) and thicker (Ts/Tt-Tgo, P < 0.05) in the supine position. The present results suggest that OSA patients are prone to significant narrowing of their oropharyngeal, but not of their naso- or hypopharyngeal, airways in the supine position. Thus, treatment of OSA and UARS patients should mainly be aimed at preventing further oropharyngeal airway narrowing as a result of supine-dependent sleep.