Botulinum Toxin-Based Study: Histological Changes in the Rabbit Vocal Folds and Construction of the Voice Rest Model With Different Rest Durations.

Abstract

There is currently no unified standard for optimal voice rest following vocal fold surgery, and inconsistencies in related clinical trials highlight the necessity of basic scientific research. However, existing animal models for voice rest have significant limitations, and no systematic establishment of a series of animal models with varying durations of voice rest that align with clinical trends has been achieved. This study was designed in two parts. In the first part, 1 U of botulinum toxin type A was injected into the unilateral thyroarytenoid muscle of rabbits, using hematoxylin-eosin staining to assess structural changes in the vocal folds and the gray-level co-occurrence matrix method to analyze texture features, thus ruling out potential effects of botulinum toxin on vocal fold structure. In the second part, 0.025 U, 0.0625 U, 0.175 U, and 0.375 U of botulinum toxin were injected into the unilateral thyroarytenoid muscle of rabbits, and at continuous, specific time points, Kinovea 0.9.5 software was used to track and analyze changes in left-right vocal fold movement over time in laryngoscopic videos, as well as the movement ratio, to evaluate the reliability of using low-dose botulinum toxin injections to simulate an animal model of voice rest. The results showed that 1 U botulinum toxin had no effect on vocal fold structure, and doses of 0.025 U, 0.0625 U, 0.175 U, and 0.375 U corresponded to voice rest durations of 1, 3, 7, and 14 days, respectively. In conclusion, injecting different doses of botulinum toxin into the unilateral thyroarytenoid muscle can induce transient immobility of the unilateral vocal fold, establishing rabbit models for varying durations of voice rest. This study proposes an innovative method to develop voice rest models of different durations by applying low-dose botulinum toxin to the neuromuscular junction of the vocal fold, potentially aiding in research to determine optimal voice rest durations for vocal fold wound healing.