The Potential Role of Subglottal Convergence Angle and Measurement.

Summary Objective This study aimed to explore subglottal convergence angle measurement. We hypothesize that the angle will change with glottis closure condition. Changes to the angle may alter vocal fold stress distribution, which could result in vocal fold pathologies. Methods Three vocal fold positions were evaluated by the degree of glottal closure and divided into three groups. Neck computed tomographic images of the subjects were gathered, and three-dimensional (3D) models of the vocal folds and the airway were reconstructed using Mimics software, through which the subglottal convergence angle was measured. Using one-way factor analysis of variance, we compared the angle among three groups. We explored the effect of the angle on vibration based on the material oblique section stress analysis. Results The subglottal convergence angle was effectively measured from 3D models. The angle changed with degree of glottal closure, with statistically significant differences among the three groups ( P Conclusion 3D model generation from computed tomographic data is an effective method of measuring the subglottal convergence angle, which changes with the degree of glottis closure, and may affect subglottal pressure distribution in the subglottal shear or normal direction and influence vocal fold vibration.