Viscoelastic properties of rabbit vocal folds after augmentation.
BACKGROUND
Vocal fold function is closely related to tissue viscoelasticity. Augmentation substances may alter the viscoelastic properties of vocal fold tissues and hence their vibratory capacity.


OBJECTIVE
We sought to investigate the viscoelastic properties of rabbit vocal folds in vitro after injections of various augmentation substances.


METHODS
Polytetrafluoroethylene (Teflon), cross-linked collagen (Zyplast), and cross-linked hyaluronan, hylan b gel (Hylaform) were injected into the lamina propria and the thyroarytenoid muscle of rabbit vocal folds. Dynamic viscosity of the injected vocal fold as a function of frequency was measured with a Bohlin parallel-plate rheometer during small-amplitude oscillation.


RESULTS
All injected vocal folds showed a decreasing dynamic viscosity with increasing frequency. Vocal fold samples injected with hylan b gel showed the lowest dynamic viscosity, quite close to noninjected control samples. Vocal folds injected with polytetrafluoroethylene showed the highest dynamic viscosity followed by the collagen samples.


CONCLUSIONS
The data indicated that hylan b gel in short-term renders the most natural viscoelastic properties to the vocal fold among the substances tested. This is of importance to restore/preserve the vibratory capacity of the vocal folds when glottal insufficiency is treated with injections.
Hertegård
Stellan
S
Department of Logopedics and Phoniatrics, Huddinge University Hospital, Karolinska Institute, Stockholm, Sweden. stellan.hertegard@klinvet.ki.se
Dahlqvist
Ake
A
Laurent
Claude
C
Borzacchiello
Assunta
A
Ambrosio
Luigi
L
D000818:Animals; D003094:Collagen / Q000494:pharmacology* / Q000627:therapeutic use; D004548:Elasticity / Q000187:drug effects; D006820:Hyaluronic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D019736:Prostheses and Implants; D011817:Rabbits; D014827:Vocal Cords / Q000187:drug effects* / Q000601:surgery*
C048470:glutaraldehyde-cross-linked collagen; C445362:hylan-B gel; D006820:Hyaluronic Acid; D003094:Collagen