Particulate Silicone for Vocal Fold Augmentation: Morphometric Evaluation in a Rabbit Model

Abstract

To study the augmentation of the paralyzed vocal fold in response to the injection of particulate plastics in a rabbit model, we performed a prospective, experimental, and controlled study in 45 New Zealand rabbits with surgical vocal fold paralysis. We compared a control group (acute unilateral recurrent nerve section) with a group that underwent polytetrafluoroethylene (PTFE) injection and with another group that underwent polydimethylsiloxane (PDMS) injection. Equal volumes of implant material were injected. The animals were killed either 6 weeks or 6 months after intervention and compared by histomorphology using a digital measuring system. The injection sites showed a substantial foreign body giant cell reaction against the PDMS and PTFE, surrounded by a light, fibrous stroma. No differences in the frequency of displacement or disaggregation of implants were observed. No extrusion to the laryngeal lumen, signs of migration outside the larynx, or malignant changes were seen. No differences were found in the length of the vocal fold between the PDMS group and the PTFE group. The vocal fold was thicker in the PDMS group than in the PTFE group, but a statistically significant difference was found only for the anterior and middle thirds at 6 weeks. In the PDMS sample, the thicknesses were similar in the 6-week and 6-month subgroups. The group with injection of PDMS yielded histologic images compatible with greater and more stable medialization than did the group with injection of PTFE.