Effect of Medialization Thyroplasty on Glottic Airway Anatomy: Cadaver Model

OBJECTIVES:The purpose of this study was to investigate the change in airway dimensions after medialization thyroplasty (MT) using a cadaveric model. Helical computerized tomography (CT) was performed before and after placement of a silastic block in human larynges to investigate the effect on airway anatomy at the level of the glottis. Tissue density (TD) of the medialized vocal fold (VF) was documented to understand the effect on tissue displacement. STUDY DESIGN:This is a cadaveric study. METHODS:Thirteen human cadaveric larynges underwent fine-cut CT scan before and after MT was performed using carved blocks in two sizes (small block and large block [LB]). Clientstream software was used to measure laryngeal dimensions: intraglottic volume (IGV), cross-sectional area (CSA), posterior-glottic diameter (PGD), VF density (in Hounsfield units [HUs]), and anterior-posterior diameter (APD). Eight sequential axial sections 0.625 mm cuts) at the level of the true VFs were analyzed. RESULTS:There was a significant decrease between the three conditions for IGV (P < 0.0001) and CSA (P < 0.0001). TD of the VF was increased after MT as indicated by HU increase (P = 0.0003). APD was not significantly changed. PGD was significantly different between the no block to LB placement (P = 0.0012). CONCLUSIONS:MT significantly changes the IGV and CSA at the level of the glottis. Density in the true VF was significantly increased. These findings have important implications for understanding volumetric effects of MT.