Chronic tympanic membrane perforation: Histopathological evidence of the experimental model.

Objectives: This study aims to compare the effectiveness of three different models of chronic tympanic membrane perforations.

Materials: The experimental study included 18 male chinchillas, divided into 3 equal groups. Group 1 perforations were performed with infolding technique myringotomy. Laser myringotomy was performed for perforation creation in Group 2. Group 3 perforations were performed with infolding myringotomy combined with ventilation tube insertion. At the end of the follow-up period, which lasts 8 weeks, all tympanic membranes with patent perforations were examined histologically.

Results: Although, the mean perforation patency in Group 2 was significantly higher than in Group 1 (5 vs. 2.4 weeks, p < 0.01), both of them failed in creation of chronic perforation according to time parameters. Group 3 demonstrated the longest mean perforation patency among investigated models (8 weeks). In Group 3, histological examination of perforations, which were considered to be chronic, revealed, that stratified squamous epithelium continued from the lateral surface around the perforation edge to join with the medial mucosal layer of TM.

Conclusion: Our findings demonstrated that the combination of infolding technique and ventilation tube insertion seems to be a potential candidate for an effective animal model of tympanic membrane perforation. Further large-scale studies are required to verify our promising results.