Upper airway (UA) anatomical abnormalities are frequently observed in obstructive sleep apnea syndrome (OSAS). The correspondence between UA anatomical modifications and UA resistance (UAR) had not been studied. We aimed to determine if cephalometric characteristics could be related to segmental UAR. In twenty-five patients (21 males) (15 OSAS patients, 10 snorers) and 10 control subjects (8 males), segmental UAR were measured in supine position and cephalometry was performed. Inspiratory and

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... piratory UAR were calculated at peak flow. Length of the soft palate (LP), posterior airway space (PAS), distance from hyoid bone to mandibular plane and to posterior pharyngeal wall were different between the groups (PB0.01). Inspiratory and expiratory, total and segmental, UAR were higher in OSAS (PB0.001). Segmental UAR were correlated with PAS and distance from hyoid bone to mandibular plane and to pharyngeal posterior wall (PB0.05). In conclusion, OSAS patients had higher UAR depending on anatomical variables, especially the place of the hyoid bone.