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.
Acoustic neuromas (ANs) are schwannomas of the eighth cranial nerve that typically arise in the vicinity of the vestibular ganglion (Scarpa's) at the junction of peripheral and central myelin (Schwann-glial junetion).' This junction usually lies within the internal auditory canal (lAC). 2 ANs enlarge medially from the lAC to involve the cerebellopontine angle (CPA) cistern and eventually interface the brainstem.!" Lateral spread of the AN from the lAC, to involve the inner and middle ear space, is exceedingly rare.We report a case involving a patient with an AN that spread laterally from the lAC to involve the cochlea, semicircular canals, and middle ear space. The potential causes of schwannoma involvement in the middle and inner ear are reviewed and the mechanism by which an AN may invade the inner ear is explored.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.