Measuring the Posterior Airway Space: Inaccuracies in Taking and Interpreting Lateral Cephalograms

Abstract Objectives Although lateral cephalograms (LCs) are often used to measure the posterior airway space (PAS), little consensus has been reached on standardised PAS measurement procedures, which hinders reproducibility. This study uses LCs to evaluate the reliability of PAS measurements and explore potential inaccuracies. Methods Two examiners measured the PAS dimensions of different LCs from the same patient, addressing deviations between examiners and variations among LCs. This study included a retrospective analysis of LCs from 45 patients, considering intrarater and interrater reliability, as well as the impact of cervical spine inclination on PAS measurements. Results The results revealed a correlation between the degree of cervical spine inclination and the PAS score. Despite a highly reliable measurement protocol, significant variabilities were observed in measurements from different LCs of the same patient. Conclusion This study highlights the need for consistent patient positioning and suggests further investigations into factors such as swallowing and breathing to increase the reproducibility of PAS measurements using LCs. These findings have implications for refining radiographic protocols and improving the reliability with which the PAS can be assessed, with the potential to serve as a screening tool that identifies patients who should undergo further diagnostic measurements, such as polysomnography. Trial Registration German Clinical Trials register (No. 348 DRKS00029159).