An Animal Model of Chronic Tympanic Membrane Perforation

Abstract

Previous investigations into the healing and reconstruction of tympanic membrane (TM) perforations have involved animal models with acute TM perforations. A problem with the acute TM perforation model is that most acute TM perforations will heal spontaneously, both in animals and human beings. A second inadequacy of acute perforation models is that they are not analogous to the salient problem in human beings: long-standing TM perforation. The ideal animal model must have a TM perforation that is permanent, well-epithelialized, and free from infection. The perforation must also be subtotal to preserve a rim of membrane for experimental manipulations. In the chinchilla, we have identified a hardy animal with a short, wide ear canal and relatively large tympanic membranes. Thermal myringectomy, followed by medial infolding of TM microflaps, has resulted in permanent, subtotal chronic TM perforations in the chinchilla animal model. Of the 19 chinchillas (38 TMs) perforated, chronic subtotal perforations were created in 32 ears, 6 to 8 weeks after the initial procedure (84% success). Persistent infection or TM regeneration despite reperforation was recorded in 6 ears (16%) failure). This model is currently being used to assess various biomembrane scaffolds impregnated with growth-promoting substances in the regeneration of a physiologically sound TM, initially in our animal model and then in human beings. We envision the development of a biomembrane disc impregnated with biorecombinant growth factors that may provide a simple office technique for the repair of chronic, non-infected TM perforations.

Searching for a rat model of chronic tympanic membrane perforation: Healing delayed by mitomycin C/dexamethasone but not paper implantation or iterative myringotomy

“…Laidlaw et al [17] applied re-myringotomy in chinchillas and reported chronic TMP in 85% of animals after a period of five to eight weeks. Numerous studies have evaluated re-myringotomy technique in combination with thermal injury and/or infolding technique showing variable success rates ranging from 69-100% [18][19][20][21][22][23][24][25][26].…”

Miringoplastia com a utilização de um novo material biossintético

“…Histologicamente, a membrana timpânica apresenta 3 camadas: uma camada epitelial, composta por duas fileiras de células epiteliais; uma intermediária fina de constituição fibrosa, com fibras de natureza colágena, fibroblastos e células endoteliais e uma média de natureza mucosa, que se continua com a mucosa do ouvido médio [3][4][5][6][7] .…”

Ein verbessertes Tiermodell f�r chronische Trommelfellperforationen

“…Meerschweinchen und Chinchillas vor[1,6,26,31,32].Da die Trommelfellreparation bei diesen Tieren schnell und hartnäckig erfolgt, spricht man bei Persistenz des Defektes über 5-8 Wochen von chronischen Perforationen [1, 22, 31]. Wir haben im vorliegenden Versuch einen Zeitraum von 8 Wochen gewählt und die Ratte aufgrund einer dem Menschen ähnlichen Trommelfellstruktur [28] sowie aus Preisgründen bevorzugt.…”