Abstract
Problem Gelfoam has been used for decades in otologic surgery to support grafts and prostheses despite causing fibrosis and adhesions. More biocompatible packing materials could avoid these complications. This study compares Gelfoam with an injectable esterified hyaluronic acid, Merogel, as middle ear packing material after mucosal trauma. Methods A randomized, blinded, controlled study was performed in 17 juvenile guinea pigs. Middle ear surgery with mucosal trauma was performed and middle ears were packed with Merogel or Gelfoam; unpacked contralateral ears were used as controls. Auditory brainstem response (ABR) thresholds were measured in 4 frequencies pre-operatively, and repeated at 1, 2, and 6 weeks postoperatively. Gross analysis measured inflammatory reaction in each group. Statistical analysis was performed using ANOVA followed by post-hoc analysis for ABR thresholds and packing remaining at 6 weeks. Non-prametric tests were used for presence of mucosal inflammation, effusion and tympanic membrane perforation. Results ABR threshold changes from baseline were minor and comparable between the Merogel group and the control group. Threshold change was higher in the Gelfoam group. This difference was seen in each frequency tested at each time interval (all p<0.05). Gross analysis showed 1) Mucosal inflammation higher in the Gelfoam group (p<0.05), 2) Effusions were higher in the Gelfoam group but the difference was not significant (p=0.07), 3) Tympanic membrane perforation was equally rare between groups (p>0.05), 4) Unabsorbed packing was higher in the Gelfoam group (p<0.05); little Merogel was detectable at time of sacrifice. Conclusion Middle ear healing after surgery occurred similarly in the control group and the Merogel group. In contrast, the Gelfoam group demonstrated greater perturbation of hearing and a greater inflammatory reaction. Significance These results support Merogel as an alternative to Gelfoam in middle ear packing after otologic surgery. Support Research grant from Medtronic ENT.