| Abstract: | In comparisons of the shape of anatomical structures in humans, size variation becomes nothing but statistical noise. Size effect is often so strong that it might mask an underlying biological factor that the study was designed to investigate. A coordinate data analysis technique allowed us to standardize size variation and showed the differences in the shape of anatomical structures between obstructive sleep apnea (OSA) patients and non-apneic subjects. A set of coordinate data, obtained from 80 pairs of lateral cephalograms taken in the upright and the supine position in the awake state, was utilized to determine the shape difference of the face and tongue of OSA patients, in comparison to those of non-apneic patients. As symptoms become severe, the hyoid bone and the submental area positioned inferiorly, and the fourth vertebra relocated posteriorly with respect to the lower mandibular border. When subjects changed their body position from the upright to supine, the posterior part of the tongue appeared to sink down, perhaps due to gravitational pull. The study clearly demonstrates that hyoid bone position with respect to the epiglottis-retrognathion line can distinguish OSA patients from non-apneic normal subjects in the supine position. Overall, analyses of the data in coordinate form provide a new prospective in OSA study. |
