Quantitative evaluation of laryngeal function in glottal insufficiency animal model for tissue engineering approach

Abstract

Injection laryngoplasty is widely used for treatment of vocal fold palsy. To test the efficacy and safety of newly developed injection materials for vocal fold augmentation, we need reliable animal model for objective evaluation of glottal insufficiency. In this study, we aimed to develop an animal model to quantitatively evaluate the histological and functional changes of the paralyzed vocal fold. Left side recurrent laryngeal nerves were identified at tracheoesophageal groove of the New Zealand white rabbits and they were resected. Endoscopic examination was performed immediately after operation and 1, 2, 4, 8, 12 week after the operation to identify left vocal fold immobility. Total laryngectomy was performed 1, 2, 4, 8, 12 weeks after the operation. We have developed the method to quantify the changes of the intralaryngeal muscles. Histologic exam revealed significant decrease in thyroarytenoid muscle volume in the paralyzed side 12 weeks after the operation. We have also developed the method to quantify the laryngeal functions by analyzing vocal fold vibration. High speed recording of induced phonation showed irregular and asymmetric movement of vocal fold in the glottal insufficiency model. Videokymographic analysis showed increased open quotient and asymmetric index compared with the normal vocal fold. This model could be used to provide fundamental changes related with vocal fold paralysis. Even more, this animal model could be utilized to test efficacy and safety of various injection materials to augment the vocal fold.