Vocal Tradeoffs in Anterior Glottoplasty for Voice Feminization.

Abstract

Objectives/hypothesis: Anterior (Wendler) glottoplasty has become a popular surgery for voice feminization. However, there has been some discrepancy between its theoretical pitch-raising potential and what is actually achievable, and downsides to shortening the glottis have not been fully explored. In addition, descriptions of the surgery are inconsistent in their treatment of the vocal ligament. This study aimed to determine 1) how fundamental frequency (f_o ) is expected to vary with length of anterior glottic fixation, 2) the impact of glottic shortening on sound pressure level (SPL), and 3) the effect of including the ligament in fixation.

Study design: Computational simulation.

Methods: Voice production was simulated in a fiber-gel finite element computational model using canonical male vocal fold geometry incorporating a three-layer vocal fold composition (superficial lamina propria, vocal ligament, and thyroarytenoid muscle). Progressive anterior glottic fixation (0, 1/8, 2/8, 3/8, etc. up to 7/8 of membranous vocal fold length) was simulated. Outcome measures were f_o , SPL, and glottal flow waveforms.

Results: f_o increased from 110 Hz to 164 Hz when the anterior one-half vocal fold was fixed and continued to progressively rise with further fixation. SPL progressively decreased beyond 1/8 to 1/4 fixation. Inclusion of the vocal ligament in fixation did not further increase f_o . Any fixation increased aperiodicity in the acoustic signal.

Conclusions: The optimal length of fixation is a compromise between pitch elevation and reduction in output acoustic power. The simulation also provided a potential explanation for vocal roughness that is sometimes noted after anterior glottoplasty.

Level of evidence: NA Laryngoscope, 131:1081-1087, 2021.