Histologic Study of an Autologous Fat Graft in the Larynx of Dogs With Unilateral Vocal Fold Paralysis

Abstract

To determine the histologic finds of autologous fat graft (AFG) in 24 paralyzed canine left vocal folds 12 weeks after introduction. Animal model. Experimental prospective study. Twenty-four mongrel dogs of both genders weighing 15 to 20 kg were divided into three study groups (SGs) of eight dogs each, whose larynges were grafted by vocal fold lipoinjection (VFL-SGA), vocal fold lipoinjection plus insulin (VFLI-SGB), and by fat graft medialization laryngoplasty (FGML-SGC), respectively, and observed for 12 weeks, followed by immediate sacrifice. All 24 dogs were submitted to left vagal and recurrent laryngeal nerve resection. All animals were confirmed to have a left vocal fold paralysis four weeks later, when 2 mL of autologous fat graft were placed inside the left paraglottic space. The larynges were removed at pre-established times and, after they were studied for remaining fat graft volume by magnetic resonance imaging, they were studied histologically to evaluate the influence of the different techniques on the histologic behavior of the graft. Each of the three study groups had its specific finds for fat graft detection and fat absorption, and its characteristics identified and compared statistically. The groups were not statistically different. The histologic findings for the AFG applied to a vocal fold were similar in groups VFL-SGA, VFLI-SGB and FGML-SGC 12 weeks after grafting, with no statistically significant differences between groups, and revealed an almost total loss of the grafted fat.