Reconstruction of vocal fold using a fat block implant following cordectomy through a minithyrotomy approach in a rabbit model

Abstract

Following transoral laser surgery for glottic cancer, the vocal fold musculature is usually resected, resulting in a concave configuration of the fibrotic neocords, leading to incomplete glottal closure.1 This causes the voice to become hoarse and breathy, and the patient’s quality of life is worsened despite the cancer possibly being cured.Several voice restoration techniques, such as injection laryngoplasty and medialization thyroplasty, have been introduced to reestablish glottal competency.2 However, these techniques only move the fibrotic vocal fold to the midline and do not in fact correct the excavated fibrotic vocal fold.Minithyrotomy is a novel approach that provides direct access to the lamina propria and vocalis muscle without requiring incision of the vocal fold mucosa. This procedure can create a ‘tunnel pocket’ space within the fibrotic vocal fold before insertion of implant materials. Thus, it is possible to place the vocal fold bulge at the midline and to directly correct the concave fibrotic vocal fold.3Twenty five adult female conditioned laboratory rabbits were used for this study. Minithyrotomy vocal fold reconstruction was performed using a single fat block implant or hyaluronic acid derivatives (®Rofilan, Rofil Medical International NV, Breda, Netherlands) 3 months after cordectomy. For the single fat block minithyrotomy reconstruction, a rabbit larynx was harvested at 1 and 6 months following minithyrotomy, and control rabbit larynges were harvested at 4 and 9 months after cordectomy. For the hyaluronic acid minithyrotomy reconstruction, rabbit larynx was harvested at 3 months following minithyrotomy.To compare total square amount and density of vocal folds between the minithyrotomy and cordectomy group, hematoxylin and eosin, masson’s trichrome, and alcian blue staining were used. Based on histological examinations, minithyrotomy vocal fold reconstruction postoperatively restored vocal fold bulkiness and maintained volume for up to postoperative 6 months, compared with the cordectomy group (P < 0.05). In light of the surgical manipulation, the procedure also did not aggravate scarring of the cordectomized vocal fold.Based on findings of this study, minithyrotomy vocal fold reconstruction using an autologous fat block may soon be feasible in humans undergoing rehabilitation for post-cordectomy dysphonia without causing additional damage to the vocal folds.