Comparison of upper airway measurement by lateral cephalogram in upright position and CBCT in supine position

Abstract

Background/Purpose Obstructive sleep apnea syndrome (OSAS) is a common form of sleep disorder. Lateral cephalograms and cone-beam computed tomography (CBCT) have been used for evaluation. However, it is lack of position comparison for these two assessments. Therefore, this study was aimed to evaluate the difference of upper airway measurements taken from lateral cephalograms in upright position and CBCT in supine position. Material and methods This retrospective study enrolled patients with lateral cephalograms and CBCT images due to diagnostic necessity. The anterior-posterior distance of most constricted area in pharynx (PASmin) and the distance from mandibular plane to hyoid bone (MP-H) were identified and measured from 21 normal subjects without obstructive sleep apnea (9 males and 12 females, mean age 21.2 years). A paired data were measured from lateral cephalograms taken in upright position and lateral cephalometric images derived from CBCT taken in supine position. Both images were taken within two months. All data were analyzed statistically. Results No significant difference was identified in intra-examiner reliability (P > 0.05). PASmin measured from lateral cephalograms in upright position was larger than that taken from CBCT derived cephalometric images, but without statistical significant difference (P = 0.073). Significant difference of MP-H length was identified between two different image taking methods (P = 0.000), and the measurement was significantly larger in cephalograms taken from upright position. No correlations were found among the variables (Body Mass Index (BMI), age, gender) in this study. The only two variables correlated were PASmin and MP-H, and they were negatively correlated (r = −0.535). Conclusion The anterior-posterior distance of most constricted area in pharynx (PASmin) and distance of mandibular plane to hyoid bone (MP-H) can be influenced due to change of body position.

Elevated Hyoid Bone Position in Response to Mandibular Advancing Appliance Predicts Effectiveness of the Appliance for Obstructive Sleep Apnea

“…In fact, Pcrit and pharyngeal dilator muscle activity (which is equivalent to Eckert et al's "UA collapsibility" and "muscle responsiveness") are sleep-stage dependent (37). Predictability of H-MP for OSA severity are high (1,2) and is greater than those of minimal posterior airway space (PAS) measurements as has been previously reported (38). As reported by Wheatley et al (8) and this study, the average amount the hyoid bone elevation by AMP use is ∼5 mm.…”

“…The hyoid bone moves superiorly in the supine position in asymptomatic subjects, while the tongue mass sinks by 30% due to gravitational pull, as the oropharyngeal space is reduced by 30% (6,38). In the supine body position, tongue and suprahyoid electromyogram (EMG) activity (principally the genioglossus) increases by 30%.…”

Cone beam computed tomographic evaluation of pharyngeal airway in North Indian children with different skeletal patterns

“…Hsu et al [ 17 ] further found that the minimum of PAS and linear distance along perpendicular changes from the most upper anterior point of the hyoid bone to mandibular plane, as the position of body is changed from upright to supine[ 17 ]. Nevertheless, in recent times, advancements in CBCT have permitted axial CT images to be acquired in upright sitting posture, which is more valid for our study.…”

CBCT in evaluating the upper airway changes and respiratory functions in patients with OSAHS

“…In our study CBCT was done in upright position for the evaluation of OSAHS. A study conducted by Wun Eng Hsu et al 23 to evaluate the change in upper airway measurements comparing lateral cephalogram in upright position and CBCT in supine position suggested that, mean anterior-posterior distance in the oropharynx and mandibular plane to hyoid bone distance can be influenced by the change in the body posture 23 .…”