Treatment of vocal fold scarring: rheological and histological measures of homologous collagen matrix.
ABSTRACT The current treatment options for dysphonia secondary to vocal fold scarring are limited. Few studies address changes in the lamina propria, which is critical to vocal fold biomechanical properties and voice production. Using rheological and histological measures of homologous collagen matrix (HCM)-injected vocal folds, we assessed HCM's potential for providing bulk and restoring biomechanical performance. Twenty rabbits underwent bilateral vocal fold scarring. After 10 weeks of scar maturation, the rabbits had unilateral injections of HCM or saline solution. Ten weeks after the injections, histological studies revealed well-defined collagen globules distributed throughout the lamina propria and underlying muscular tissue. Significantly more procollagen was observed in the HCM-treated group. No significant differences in elastic shear modulus or dynamic viscosity were found between the treatment groups. This study demonstrates that HCM is an inert, relatively stable injectate that may serve well for medialization but does not appear to improve the dynamic properties of the lamina propria.
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ABSTRACT: The Linear Skin Rheometer (LSR), which measures skin visco-elasticity, was adapted for measurements of vocal fold properties. In excised larynges small patches of mucosa were driven sinusoidally at .3 Hz over 1-2 mm distances using a small probe. Forces on the order of one gram gave optimal measurements. Stiffness and viscosity values were derived from stress/strain data and using a simple shear model. The instrument was able to measure the visco-elasticity of the tissue in a repeatable manner and it could detect areas where the tissue was artificially stiffened. 2D maps of the viscous and elastic properties of the laryngeal mucosa were obtained showing local variations in elasticity and viscosity both parallel and perpendicular to the vocal fold edge. Introduction: In phonosurgery there is a need for an instrument that can measure the material properties of the superficial lamina propria of the vocal fold, a layer that is critical for normal phonation, that is frequently damaged and that is a key target for novel vocal fold augmentation techniques. Such an instrument would ideally help the surgeon sense the extent and degree of tissue abnormality and provide objective measures before, during and after treatment.
Article: In vivo measurement of the shear modulus of the human vocal fold: interim results from eight patients.[show abstract] [hide abstract]
ABSTRACT: The shear modulus of the vocal fold is an essential parameter required to enhance our understanding of how the vocal fold operates, to develop mathematical models of phonatation, and to provide benchmarks to quantify the effectiveness of surgical procedures. The authors announced the successful deployment of an instrument to measure vocal fold elasticity in vivo last year, and now present the data taken from eight patients in vivo. The shear modulus was measured at the mid-membranous point, in a transverse direction with respect to the axis drawn between the anterior commissure and vocal process. The range of mean shear modulus results is 701-2,225 Pa, with a mean value of 1,371 Pa.Archiv für Klinische und Experimentelle Ohren- Nasen- und Kehlkopfheilkunde 07/2007; 264(6):631-5. · 1.29 Impact Factor
Article: [Vocal fold superficial layer of lamina propria histology after the position of mucosa pediculated flap: canine experimental study].[show abstract] [hide abstract]
ABSTRACT: Many techniques were applied to treat patients with sulcus vocalis and scarred vocal folds. Their results were not good enough. In the Technique of Vocal Fold Pediculated Mucosa Flap, an anterior pediculated flap of vocal fold is positioned on the superficial layer of the lamina propria, below the free margin. To describe histological postoperative findings on the superficial layer of lamina propria during the application of the technique Vocal Fold Pediculated Mucosa Flap. The following parameters were compared between tested and control groups: total, type I and type III collagen and number of cellular nucleus. experimental. Fifteen dogs were used. One vocal fold was submitted to the intervention and the other was left as control. Each group of three dogs was sacrificed on 10, 30, 90, 180 and 360 days after the experimental surgery. Hematoxylin and eosin (H.E.) and Syrius Red were the staining techniques used. Type I and total collagen suggested increased results in the tested group on postoperative days 90 and 180, nevertheless there was statistical significance only on postoperative day 180 (p<0.05). Type III collagen group area was less significant than the control group on postoperative day 180 (p<0.05). The number of cellular nucleus was increased on the 10th postoperative day, but decreased after the 30th day. The findings about total and type I collagen and the amount of cellular nucleus on the superficial layer of lamina propria were similar to laryngeal postoperative studies in dogs. More complex studies would contribute with new data about the present subject.Brazilian journal of otorhinolaryngology 71(3):318-24.