Evaluation of esterified hyaluronic acid as middle ear-packing material

Objective: To evaluate the efficacy of esterified hyaluronic acid (MeroGel) as a middle ear (ME)-packing material. Design: Randomized controlled trial. Material: Twenty-four guinea pigs. Intervention: Group 1,MeroGel-treated animals (n= 10), bilateral wounding of ME mucosa with 5 of the animals receiving the MeroGel packing in the left ME and 5 of the animals receiving MeroGel in the right ME; group 2, absorbable gelatin sponge-treated animals (n= 10), with the same experimental protocol as in group 1 except that the absorbable gelatin sponge was the packing material; group 3, untreated animals (n=4), unilateral wounding of the left ME mucosa in 2 animals and in 2 animals in the right ME. with no packing material. Auditory brainstem recordings were performed for all groups before the ME operation and 5 days and 6 weeks after the operation. Results: Auditory brainstem response recordings at postoperative day 5 showed that all ears with ME packing had hearing losses in the frequency range of 500 to 4000 Hz, The recovery of hearing acuity at postoperative week 6 was significantly better in group 1 (MeroGel-treated) guinea pigs compared with group 2 (the absorbable gelatin sponge-treated) animals. In group 2 animals, 20% of the packing material remained in the ME cavities and new bone formation was observed, while in group 1 animals, there was less packing material in the ME and no formation of new bone. Conclusions: MeroGel is a nonototoxic packing material with a high level of biocompatibility for ME mucosa; it is an effective supportive material following ME surgery and is easily expelled from the ME cavity.