Change of Phonation in Canines Without Vocal Fold Paralysis After Vocal Processes Resection

The effects of the vocal processes resection on phonation in an animal without vocal fold paralysis have not been clarified. The present study used an in vivo animal model with vocal processes resection and excised larynges phonation model to investigate the effects of the vocal processes resection on phonation. Six months after resection of bilateral vocal fold processes, glottal airflow, subglottal air pressure, acoustic signals, and ultra-high-speed video images were recorded in the excised larynges phonation model of canine. Glottal aerodynamic parameters were estimated by calculation of subglottal pressure and glottal flow. Histological analyses of the scarred were assessed for wound healing completion. In the vocal processes resection group, fundamental frequency(F₀) and vocal intensity decreased, and the Jitter and Shimmer increased significantly. The phonation threshold power(PTW) of the vocal processes resection was significantly higher than controls. The vibratory amplitude of the vocal fold posterior and visual vocal fold vibration length increased. Expression of collagen I-III in scarred tissue samples in vocal process resection was similar to controlling soft tissue specimens around vocal process cartilage, and collagen fiber formed matured thick bundles. The results suggest that the F₀, voice quality, and vocal intensity significantly decreased after complete wound healing of vocal processes resection in canines without vocal folds paralysis. The higher PTW and posterior scarred vocal vibration may be the dynamic reasons.