Abstract:

Objective    To assess the correlation of hyoid position, minimal section area of retroglossal space and severity of patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods    57 adult OSAHS patients, diagnosed by polysomnography (PSG), were included in the study, and the apnea-hypopnea index (AHI) was used as an indicator for the severity of OSAHS. All the patients underwent upper airway 64-row CT scanning in supine and FH perpendicular to the ground position.  The computerized 3D reconstruction technique was used to reconstruct the sagittal and axial images. With the help of sagittal images, the angle between the hyoid bone and mandibular planes (α) was measured and used as the indicator for the vertical position of the hyoid bone; Meanwhile, the ratio(R) of hyoid-anterior mandible distance to hyoid-posterior mandible distance was measured and used as the indicator of the anteroposterior position of the hyoid bone. With the help of axial images, the sectional area (s) of the retroglossal space was measured. The correlation of such indexes as, R, s, as well as AHI were analyzed by SPSS.  Results    In 57 cases,α positively correlated with AHI (R=0.305, P=0.021).  There was no correlation between AHI and R . Both α and R didn′t show any correlation with s. Conclusion    In OSAHS patients, the severity of the disease is related to the position of the hyoid bone. With the advancement of OSAHS, the position of the hyoid tends to move downwardly. The possible causes could be the aggregation of soft tissues, such as fat and etc., at the mouth floor and the hypofunction of muscles related to the hyoid. But, under its natural condition, the change of the hyoid position in OSAHS patient would not lead to the transformation of the sectional area  of the retroglossal space.

Key words: Obstructive sleep apnea hypopnea syndrome, Hyoid bone, Computed tomography