Author(s)
Nikhil Arora, MD
Yue Ma, MD
VyVy N. Young, MD
Sarah L. Schneider, CCC-SLP
Clark A. Rosen, MD
Tyler W. Crosby, MD
Affiliation(s)
UCSF Voice & Swallowing Center, Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, CA
Abstract:
Objective: Study of the modified Wendler glottoplasty (MWG) typically focuses on the anterior-posterior (AP) dimension of the glottic web as a proportion of vocal fold (VF) length. We sought to investigate the relevance of its craniocaudal dimension to determine whether thick infraglottic web geometry produces greater fundamental frequency (F0) elevation than a thin web of equivalent AP dimension.
Methods: Eight porcine larynges were prepared by removal of supraglottic structures. Compressed air was passed through the glottis with gentle traction of the muscular processes to achieve phonation under three conditions: baseline, thin web, and thick web. For the thin web, an anterior suture was placed at a mean of 37% of VF length capturing only the superior free edge. For the thick web, a suture was placed at the same AP position but directed to exit beyond the inferior free edge, capturing the entirety of the infraglottic vibratory surface. Mean F0 was extracted from audio recordings and Wilcoxon signed-rank tests were used to compare F0 elevation of each web geometry to baseline and between the two geometries.
Results: Median F0 at baseline was 361.5 Hz (IQR: 308.7–392.0 Hz). The thin web did not produce a statistically significant F0 elevation relative to baseline (Bonferroni-adjusted p = 0.445; Hodges-Lehmann [HL] shift: 162.6 Hz, 95% CI: -39.3–382.5 Hz). The thick web produced a statistically significant elevation in median F0 to 652.0 Hz (IQR: 491.0–779.7 Hz) relative to baseline (Bonferroni-adjusted p = 0.023; HL shift: 255.4 Hz, 95% CI: 68.1–452.9 Hz). Direct comparison between web geometries was significant non-adjusted but did not reach significance after Bonferroni correction (p = 0.039; adjusted p = 0.117).
Conclusion: Vocal fold vibration is a three-dimensional (3D) phenomenon with propagation of the mucosal wave from the infraglottic vocal folds. This model demonstrates the relevance of the 3D geometry of a glottic web in MWG, with impacts not only from the AP dimension of the web but also from incorporation of the infraglottic vibratory surface. Deliberate infraglottic capture may represent a technically modifiable variable to optimize pitch elevation outcomes in gender-affirming voice surgery.