The effects of different packing materials on healing and hearing after trauma to middle ear mucosa, an experimental study in rats

Purpose: To compare the performance of Spongostan, Otopore, Spongostan soaked with dexamethasone and Spongostan soaked with Hyaluronic acid (HA) as middle ear packing material after mucosal trauma. Methods: Twenty rats were divided into 4 groups. In control group (group 1), the middle ear cavities of animals were bilaterally packed with Spongostan; in group 2, with Otopore; in group 3, with Spongostan soaked with dexamethasone; and in group 4, with Spongostan soaked with HA. Auditory brainstem responses (ABRs) were performed preoperatively and 1 and 6 weeks postoperatively. Histological analyses were performed to evaluate the inflammatory reaction and wound healing in the middle ear cavity. Results: ABR recordings demonstrate that threshold level changes from baseline were minor in Otopore and Spongostan soaked with dexamethasone packed ears. Threshold levels were higher in the Spongostan and Spongostan soaked with HA packed ears compared with both Otopore and Spongostan soaked with dexamethasone packed ears. Histological analyses showed that Spongostan caused inflammation more intense than Otopore and Spongostan soaked with dexamethasone. Residual material at postoperative week 6, new bone formation and adhesion were common in the Spongostan group compared with other groups. Fibrosis was more common in Spongostan group compared with other groups but the difference was not significant. Conclusion: Otopore appears to be safe and effective for use in otologic surgery. The inflammation, adhesion and new bone formation decreased when Spongostan was used with steroid or HA, when compared to Spongostan alone.