Figure 2 Measurement of glottic entrance parameters. (A) Cross-reference of sagittal image helps to find location of glottic entrance. Most of them are located at the level of epiglottic cartilage, but in some patients the narrowest plane is regarded as the glottic entrance. (B) Sagittal diameter is the distance from anterior end and posterior end of glottic entrance (line a). Transverse diameter is the broadest distance between lateral sides. (C) Cross-section area is measured by linking points on the medial wall of the glottic entrance.