A Rat Excised Larynx Model of Vocal Fold Scar PurposeTo develop and evaluate a rat excised larynx model for the measurement of acoustic, aerodynamic, and vocal fold vibratory changes resulting from vocal fold scar.MethodTwenty-four 4-month-old male Sprague–Dawley rats were assigned to 1 of 4 experimental groups: chronic vocal fold scar, chronic vocal fold scar treated with 100-ng basic fibroblast ... Article/Report
Article/Report  |   August 01, 2009
A Rat Excised Larynx Model of Vocal Fold Scar
 
Author Affiliations & Notes
  • Nathan V. Welham
    University of Wisconsin School of Medicine and Public Health, Madison
  • Douglas W. Montequin
    The National Center for Voice and Speech, The Denver Center for the Performing Arts, Colorado
  • Ichiro Tateya
    Kyoto University, Japan
  • Tomoko Tateya
    Kyoto University, Japan
  • Seong Hee Choi
    University of Wisconsin School of Medicine and Public Health, Madison
  • Diane M. Bless
    University of Wisconsin School of Medicine and Public Health, Madison
  • Contact author: Nathan V. Welham, University of Wisconsin School of Medicine and Public Health, K4/723 CSC, 600 Highland Avenue, Madison, WI 53792. E-mail: welham@surgery.wisc.edu.
Article Information
Speech, Voice & Prosodic Disorders / Voice Disorders / Speech, Voice & Prosody / Speech
Article/Report   |   August 01, 2009
A Rat Excised Larynx Model of Vocal Fold Scar
Journal of Speech, Language, and Hearing Research, August 2009, Vol. 52, 1008-1020. doi:10.1044/1092-4388(2009/08-0049)
History: Received March 1, 2008 , Accepted October 12, 2008
 
Journal of Speech, Language, and Hearing Research, August 2009, Vol. 52, 1008-1020. doi:10.1044/1092-4388(2009/08-0049)
History: Received March 1, 2008; Accepted October 12, 2008
Web of Science® Times Cited: 33

PurposeTo develop and evaluate a rat excised larynx model for the measurement of acoustic, aerodynamic, and vocal fold vibratory changes resulting from vocal fold scar.

MethodTwenty-four 4-month-old male Sprague–Dawley rats were assigned to 1 of 4 experimental groups: chronic vocal fold scar, chronic vocal fold scar treated with 100-ng basic fibroblast growth factor (bFGF), chronic vocal fold scar treated with saline (sham treatment), and unscarred untreated control. Following tissue harvest, histological and immunohistochemical data were collected to confirm extracellular matrix alteration in the chronic scar group; acoustic, aerodynamic, and high-speed digital imaging data were collected using an excised larynx setup in all groups. Phonation threshold pressure (Pth), glottal resistance (Rg), glottal efficiency (Eg), vibratory amplitude, and vibratory area were used as dependent variables.

ResultsChronically scarred vocal folds were characterized by elevated collagen Types I and III and reduced hyaluronic acid abundance. Phonation was achieved, and data were collected from all control and bFGF-treated larynges; however, phonation was not achieved with 3 of 6 chronically scarred and 1 of 6 saline-treated larynges. Compared with control, the chronic scar group was characterized by elevated Pth, reduced Eg, and intralarynx vibratory amplitude and area asymmetry. The bFGF group was characterized by Pth below control-group levels, Eg comparable with control, and vocal fold vibratory amplitude and area symmetry comparable with control. The sham group was characterized by Pth comparable with control, Eg superior to control, and vocal fold vibratory amplitude and area symmetry comparable with control.

ConclusionsThe excised larynx model reported here demonstrated robust deterioration across phonatory indices under the scar condition and sensitivity to treatment-induced change under the bFGF condition. The improvement observed under the sham condition may reflect unanticipated therapeutic benefit or artifact. This model holds promise as a tool for the functional characterization of biomechanical tissue changes resulting from vocal fold scar and the evaluation of experimental therapies.

Acknowledgments
This study was supported by National Institute on Deafness and Other Communication Disorders Grant R01 DC004428. This study was performed in accordance with the Public Health Service Policy on Humane Care and Use of Laboratory Animals (Office of Laboratory Animal Welfare, 2002), the Guide for the Care and Use of Laboratory Animals (Institute of Laboratory Animal Resources, 1996), and the Animal Welfare Act (2007); the animal use protocol was approved by the Institutional Animal Care and Use Committee of the University of Wisconsin–Madison. We acknowledge experimental setup consultation provided by Jack J. Jiang and statistical consultation provided by Alejandro Muñoz del Río.
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