Implant location in type 1 thyroplasty for unilateral vocal fold paralysis: Measurements from excised canine larynges

Abstract

Patients with unilateral vocal fold paralysis (UVFP) complain of a soft breathy voice that is hard to understand. Thyroplasty Type 1 (TT1), the most common surgical intervention for UVFP, uses an implant to push over the membranous fold. There remains controversy regarding TT1 procedures. Questions include the optimal shape and size for the implant, where to place the implant and whether an arytenoid adduction should be added. Despite several studies, no optimal technique has been found, and the revision rate has reported to be as high as 12%–25%. This study aims to understand the impact of implant location on vocal fold vibration. TT1 procedures were performed on excised canine larynges using silastica implants placed either at the glottis or just below the glottis to medialize the folds. Larynges were then made to phonate at various subglottal pressures (Psg), and measurements were taken of the acoustics, supplied flow rate, and Psg. From these measurements, the glottal efficiency was calculated, and the acoustic signal was analyzed to determine the quality of the sound source. On average, larnges medialized in the subglottis had higher glottal efficiency and cepstral peak prominence than those medialized at the glottis, indicating that lower implant location is preferable.Patients with unilateral vocal fold paralysis (UVFP) complain of a soft breathy voice that is hard to understand. Thyroplasty Type 1 (TT1), the most common surgical intervention for UVFP, uses an implant to push over the membranous fold. There remains controversy regarding TT1 procedures. Questions include the optimal shape and size for the implant, where to place the implant and whether an arytenoid adduction should be added. Despite several studies, no optimal technique has been found, and the revision rate has reported to be as high as 12%–25%. This study aims to understand the impact of implant location on vocal fold vibration. TT1 procedures were performed on excised canine larynges using silastica implants placed either at the glottis or just below the glottis to medialize the folds. Larynges were then made to phonate at various subglottal pressures (Psg), and measurements were taken of the acoustics, supplied flow rate, and Psg. From these measurements, the glottal efficiency was calculated, and th...