Cross-linked hyaluronan for augmentation of the posterior pharyngeal wall: an experimental study in rats

Velopharyngeal insufficiency can be treated in different ways. Augmentation injections of various space-filling materials have been tried, but a substance that has the ideal properties--easy to inject, non-toxic, and not immunogenic, and having a lasting effect--has not yet been found. Hylan b gel, a double cross-linked hyaluronan solution, is a new tissue augmentor that is not immunogenic and is easy to use. The purpose of this study was to evaluate the persistence of and the tissue reaction to hylan b gel injected into the posterior pharyngeal wall of 12 rats. Six rats acted as controls. A light immediate, and no late, inflammatory reaction developed in the pharyngeal mucosa after injection. Six months after injection, the gel was still present and the substance had been invaded by and surrounded by newly-formed, loose connective tissue. These results indicate that hylan b gel may be an appropriate substance in the augmentation of mild velopharyngeal insufficiency in man. However, further studies are needed to evaluate its long-term effects.