Infraglottal Medialization: Increasing Vocal Fold Stiffness Gradient for Improved Vocal Efficiency

Assess the impact of the infraglottal medialization technique on acoustics and the vertical stiffness gradient of the vocal fold using excised canine larynges.

Seven ex vivo canine larynges were tested in three states: 1) no implant, 2) medialized using a glottal implant, and 3) medialized fold using an infraglottal implant. Outcome measures were vocal efficiency and stiffness of the fold. Stiffness was measured using the indentation technique in three height levels of the fold to assess the vertical stiffness gradient.

Infraglottal medialization improved vocal efficiency in all larynges tested and was superior to the improved efficiency seen with glottal medialization. Infraglottal medialization increases the vertical stiffness gradient of the vocal fold. While glottal medialization increased overall vocal fold stiffness, it did not enhance the vertical stiffness gradient.

Infraglottal medialization improves vocal efficiency and vertical stiffness gradient. Stiffness gradient might be the mechanism behind the creation of the glottal divergent angle by infraglottal medialization, a finding that was observed in a previous study. These results provide valuable guidance to clinicians in selecting implant location and medialization techniques, offering the prospect of enhanced vocal outcomes. In addition, it sheds light on some principles in vocal fold vibration mechanics.

​Unilateral vocal fold paralysis—Medialization thyroplasty—Vertical stiffness gradient—Vocal efficiency—Intraglottal flow