A cephalometric and electromyographic study of upper airway structures in the upright and supine positions

Eung Kwon Pae, Alan A. Lowe, Keiichi Sasaki, Colin Price, Masafumi Tsuchiya, John A. Fleetham

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146 Citations (Scopus)


Obstructive sleep apnea (OSA) is characterized by recurrent upper airway obstruction during sleep, usually in the supine position. To investigate the relationship between upper airway size and genioglossus (GG) muscle activity, upright and supine cephalograms were obtained in 20 OSA patients and 10 symptom-free control subjects. Tongue electromyographic (EMG) recordings were obtained with surface electrodes, and pressure transducers were placed in the 10 symptom-free controls. The tongue cross-sectional area increased 4.3% (p<0.05), and the oropharyngeal area decreased 36.5% (p<0.01) when the OSA patients changed their body position from upright to supine. No changes were observed in the tongue area, but soft palate thickness increased (p<0.01) when the control subjects changed from the upright to the supine position. Furthermore, the oropharyngeal cross-sectional area decreased 28.8% (p<0.01) despite a 34% increase (p<0.05) in resting GG EMG activity. Posterior tongue pressure increased 17% (p<0.05) with the change from upright to supine. On the basis of these findings, we propose that body posture has a substantial effect on upper airway structure and muscle activity. This postural effect should be taken into account when assessing upper airway size in the erect posture (conventional cephalography) and in the supine position (computed tomography). The vertical and anteroposterior position of the tongue and its relationship to airway size may be more important than soft palate size in the pathogenesis of OSA.

Original languageEnglish
Pages (from-to)52-59
Number of pages8
JournalAmerican Journal of Orthodontics and Dentofacial Orthopedics
Issue number1
Publication statusPublished - 1994
Externally publishedYes

ASJC Scopus subject areas

  • Orthodontics


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