Effects of NasoPore Packing in the Middle Ear Cavity of the Guinea Pig

To evaluate the effects of NasoPore after packing of the middle ear in guinea pigs.A randomized, prospective, controlled animal study.University laboratory.Forty-one guinea pigs were divided into 3 groups. In group 1(n=12), the middle ears of animals were unilaterally implanted with NasoPore, leaving the contralateral middle ears packed with absorbable gelatin sponge soaked in a solution containing kanamycin and furosemide as an ototoxicity-positive control; group 2 (n = 17) underwent the same experimental protocol as group 1, except the gelatin sponge was unsoaked; in group 3 (n = 12), NasoPore was inserted unilaterally and no packing material was placed into the contralateral ear. Auditory brainstem responses (ABRs) were performed preoperatively and 3 months after the procedure. The surface preparation and scanning electron microscopy (SEM) were assessed 3 months postoperatively, whereas pathology of middle ear was analyzed in 5 samples of group 2.ABR thresholds of the contralateral ear significantly increased in group 1 and were slightly shifted in group 2 compared with the NasoPore-packed and nonpacked ears 3 months postoperatively. The NasoPore-packed middle ears were found to have less fibrosis and inflammation and less thickened bone and tympanic membranes than Gelfoam-packed ears. Surface preparations and SEM showed no ototoxicity in the inner ear of NasoPore-packed ears.NasoPore appears to be effective for use in otosurgery. It caused less fibrosis in the middle ear than conventional packing agents and no ototoxicity to the inner ear.