Angiogenesis, fibrinogenesis and presence of synechiae after exeresis of a swine vocal fold mucosal microflap and use of topical mitomycin-C

Vinicius Ribas De Carvalho Duarte Fonseca,Marcelo Mazza Do Nascimento,Osvaldo Malafaia,Paulo Afonso Nunes Nassif,Nicolau Gregori Czeczko,Carmen Austrália Paredes Marcondes,Jurandir Marcondes Ribas Filho

doi:10.1590/s0102-86502010000100017

Vinicius Ribas De Carvalho Duarte Fonseca, Marcelo Mazza Do Nascimento + Show 5 more

Open Access

https://doi.org/10.1590/s0102-86502010000100017

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Abstract

To evaluate swine vocal fold healing in a period of 30 days after topical mitomycin-C application. Twelve swine underwent exeresis of mucosal flaps from the free edge of the anterior third of both vocal folds with a cold instrument (laryngeal scissors). The animals were divided into two groups: EG (Experimental Group), consisting of 6 animals undergoing topical MMC application (4 mg/dL) on the operated area for 4 minutes; CG (Control Group), 6 animals undergoing topical saline solution application on the operated area for 4 minutes. After 30 days, the animals were sacrificed and the larynges were collected and examined for the presence of synechiae as well as a histological immunohistochemical assessment of immature and mature collagen deposition, number of blood vessels and myofibroblasts. Mature collagen deposition in the EG was 452.12 microm(2) and 1332.31 microm(2) in the CG; immature collagen deposition was 1511.73 microm(2) in the EG and 1020.61 microm(2) in the CG. The number of myofibroblasts was 1.556 in the EG and 3.583 in the CG. The number of blood vessels was 2.565 in EG and 6.917 in the CG. There were no synechiae in the two studied groups. There was an increase in immature collagen deposition in the experimental group when compared with the control group. There was a decrease in mature collagen deposition in the experimental group when compared with the control group. There was a decrease in the number of myofibroblasts in the experimental group when compared with the control group. A decrease in blood vessels was observed in the experimental group when compared with the control group. There was no synechia formation in either studied group.

Highlights

With the progress of laryingology over the past decades, most vocal fold disorders have become treatable
The animals were randomized into two groups: the Experimental Group (EG), composed of six animals, underwent exeresis of mucosal tissue from the free edge of the anterior third of both vocal folds with cold instruments and application of topical mitomycin-C at a concentration of 4 mg/dL for four minutes
In that study, the deposition of mature and immature collagen was not compared in the EG, which could demonstrate an induction of hypertrophic scarring

Summary

Introduction

With the progress of laryingology over the past decades, most vocal fold disorders have become treatable. Phonomicrosurgery techniques are based on the understanding of vocal fold pathophysiological mechanisms. The objective of those techniques is to minimize the development of scars, adhesions and stiffness of the mucosal lining, achieving objective and subjective vocal pattern improvement. Caused by lesions or inflammation, it damages the lamina propria of the phonatory mucosa, altering its biomechanical properties, with an increase in viscoelasticity leading to reduced vocal fold vibration and difficult-to-manage dysphonia[3]. A number of researchers have described vocal fold scarring as the result of poor and disorganized wound healing, characterized by increased density and diminished collagen organization. Normal wound healing takes place as a sequence of well-coordinated events leading to the formation of new tissue. Alterations or therapeutic manipulation during these acute stage events can be very relevant in scar formation[4]

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