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Modulating phonation through alteration of vocal fold medial surface contour

Authors

  • Ted Mau MD, PhD,

    Corresponding author
    1. Departments of Otolaryngology–Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A.
    • Department of Otolaryngology–Head and Neck Surgery, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390
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  • Joseph Muhlestein BS,

    1. Departments of Otolaryngology–Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A.
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  • Sean Callahan MD,

    1. Departments of Otolaryngology–Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A.
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  • Roger W. Chan PhD

    1. Departments of Otolaryngology–Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A.
    2. Biomedical Engineering, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A.
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  • Presented at the Triological Society Annual Meeting, San Diego, California, U.S.A., April 20–21, 2012.

  • The authors have no other funding, financial relationships, or conflicts of interest to disclose.

Abstract

Objectives/Hypothesis:

1) To test whether alteration of the vocal fold medial surface contour can improve phonation and 2) to demonstrate that implant material properties affect vibration even when implantation is deep to the vocal fold lamina propria.

Study Design:

Induced phonation of excised human larynges.

Methods:

Thirteen larynges were harvested within 24 hours postmortem. Phonation threshold pressure (PTP) and flow (PTF) were measured before and after vocal fold injections using either calcium hydroxylapatite (CaHA) or hyaluronic acid (HA). Small-volume injections (median, 0.0625 mL) were targeted to the inferomedial aspect of the thyroarytenoid muscle. Implant locations were assessed histologically.

Results:

The effect of implantation on PTP was material dependent. CaHA tended to increase PTP, whereas HA tended to decrease PTP (Wilcoxon test, P = .00013 for onset). In contrast, the effect of implantation on PTF was similar, with both materials tending to decrease PTF (P = .16 for onset). Histology confirmed implant presence in the inferior half of the vocal fold vertical thickness.

Conclusions:

Taken together, these data suggested the implants may have altered the vocal fold medial surface contour, potentially resulting in a less convergent or more rectangular glottal geometry as a means to improve phonation. An implant with a closer viscoelastic match to vocal fold cover is desirable for this purpose, as material properties can affect vibration even when the implant is not placed within the lamina propria. This result is consistent with theoretical predictions and implies greater need for surgical precision in implant placement and care in material selection. Laryngoscope, 2012

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