Estudo histológico do tecido conjuntivo areolar perifascial implantado em pregas vocais de coelhos / Histological study of implanted perifascial areolar tissue in rabbit´s vocal folds

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Besides the great development of phonosurgery over the previous decades, vocal fold stiffness is a difficult disease that remains a therapeutic challenge. It may be either caused by cicatricial fibrosis or be associated with minor structural alterations of the vocal fold mucosa, mainly represented by deep sulcus vocalis. In both cases, there is loss and disorganization of extracellular matrix components of the superficial layer of the lamina propria (Reinkes Space), which is replaced by fibrotic tissue. The treatment goal is to re-establish the physical volume and the microarchitecture of the vocal folds. The perifascial tissue consists of a loose areolar tissue with viscoelasticity properties close to those of the superficial layer of the lamina propria. Thus, the aim of this experiment was to evaluate the histological changes of the graft and in the host tissue after placing a strip of this tissue into rabbits vocal folds. Thirty rabbits were operated. The graft was implanted in pockets surgically created in the right vocal fold. The left vocal fold was used as control. The animals were randomically divided in three groups for evaluation at 15 days (Group I), 3 months (Group II) and 6 months (Group III) and their larynx reviewed histologically. Histological sections underwent hematoxylin-eosin and specific staining method to quantify collagen fibers (Picrosirius-polarization method). Histological changes of the graft were observed since 15 days post-operatively and were characterized by a progressive increase of the density of collagen fibers and decrease of vascularization. Examination of Picrosirius-red stained section with polarizing microscopy revealed a gradual change of collagen fibers pattern with a predominance of greenish-yellow range observed in the original tissue and in Group I and mostly redish-orange range in the grafts of Group II and III. Statistical analysis (Anova one-way) showed a significant increase of the liitotal collagen density in the graft between Group I and II (p=0.004) and a significant predominance of redish-orange pattern between Groups II e III (p=0.011). The collagen density of the surrounding area of the graft in the implanted vocal fold was significantly increased when compared to control in all periods (p 0.001). The inflammatory process was not statistically different between the implanted vocal folds and controls according to Fisher´s test for any of the studied groups. Nonetheless, when the inflammatory process of each vocal fold was individually assessed on a long-term basis, a significant decrease of the inflammatory process was seen in the host (p=0.032) and control vocal fold (p=0.035) between Group I and II. Our findings suggest that the PAT has some advantages as a substance for vocal fold augmentation: it has low tendency to promote inflammatory response and low rate of absorption since it remains in the vocal fold for at least six months. However, the histological changes that take place in the graft and in the host tissue suggest that the PAT is not an ideal material as a substitute for the lamina propria and new studies are needed to determine its role on the treatment of vocal fold scarring.

ASSUNTO(S)

modelos animais autologous collagen histologia vocal cords colágeno transplante autólogo animal model histology transplantation cicatriz cordas vocais cicatrix

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