Recovery of vibratory function after vocal fold microflap in a rabbit model

Abstract

Objectives/Hypothesis The purpose of this study was to evaluate the return of vibratory function and restoration of vibration amplitude and symmetry after vocal fold microflap surgery. Study Design Prospective in vivo animal model. Methods Microflap surgery was performed on 30 New Zealand white breeder rabbits. The left vocal fold received a 3-mm epithelial incision and mucosal elevation, while the contralateral vocal fold was left intact to serve as an internal control. Quantitative analysis of amplitude ratio and lateral phase difference were measured using high-speed laryngeal imaging at a frame rate of 10,000 frames per second from animals undergoing evoked phonation on postoperative days 0, 1, 3, 5, and 7. Results Quantitative measures revealed a significantly reduced amplitude ratio and lateral phase difference on day 0 after microflap. These impairments of vibratory function on day 0 were associated with separation of the vocal fold’s bodycover layer. Amplitude ratio increased significantly by day 3 after microflap, with further increases in vibration amplitude on days 5 and 7. While the amplitude ratio improved significantly on day 3, lateral phase difference decreased significantly on day 3, and returned to normal on days 5 and 7. Conclusions High-speed laryngeal imaging was used to investigate the natural time course of postmicroflap recovery of vibratory function. Results revealed the restoration of vibration amplitude and lateral phase difference by days 3 to 7 after microflap. The time period of improved vibratory function observed in this study coincides with the end of the well-documented inflammatory phase of vocal fold wound repair.

Recovery of Vocal Fold Epithelium after Acute Phonotrauma

“…These findings are consistent with previous experiments in our laboratory, showing return of vibratory function and attenuation of the inflammatory process by day 3, with evidence of active tissue remodeling 3–7 days after microflap. 22,23 …”

A rabbit vocal fold laser scarring model for testing lamina propria tissue‐engineering therapies

“…However, the much smaller size of the animal larynx often precludes the degree of precision that is possible in human vocal fold surgeries. Although vocal fold microflap elevation has been demonstrated in the rabbit, it is not meant as a way to create scar, and vibratory function returns to normal within a week . Cup forceps biopsy, which is a well‐accepted vocal fold injury method in animal models, in theory could limit the size of the mucosal defect to the size of the cup.…”

“…Although vocal fold microflap elevation has been demonstrated in the rabbit, 10 it is not meant as a way to create scar, and vibratory function returns to normal within a week. 18 Cup forceps biopsy, which is a well-accepted vocal fold injury method in animal models, in theory could limit the size of the mucosal defect to the size of the cup. In our experience, the mucosal defect tends to be larger than the cup size, because the rabbit vocal fold mucosa is highly elastic, and the defect is created by a ripping rather than cutting action.…”

Vibratory function and healing outcomes after small intestinal submucosa biomaterial implantation for chronic vocal fold scar

“…Although these proof of concept data demonstrate the safety of SIS in healthy uninjured vocal folds, the effects of SIS implantation on functional tissue outcomes following treatment of chronic vocal fold scar remains unknown. The purpose of the present study was to investigate the effects of SIS implantation on: 1) functional tissue outcomes using high‐speed videoendoscopy (HSV) and 2) wound repair using routine staining and immunohistochemistry in the treatment of chronic vocal fold scar using an in vivo rabbit phonation model . The following hypotheses were investigated: 1) SIS improves amplitude, amplitude ratio and left‐right phase symmetry over microflap elevation alone, and 2) SIS increases elastin and HA and decreases collagen types I and III after SIS implantation into the chronic scarred vocal fold over microflap elevation alone.…”