\s=b\ Experimental studies have shown that if antibiotic otic drops reach the middle ear cavity they produce severe inflammation. However, the effects of these preparations on the tympanic membrane have not been thoroughly investigated. This study was designed to assess morphological changes in the chinchilla tympanic membrane two to 21 days after a single 0.2-mL application of an antibiotic otic preparation (Cortisporin Otic Suspension) to the middle ear cavity. At two days, the epidermal and the mucosal layers were destroyed. By four days, reepithelialization had occurred and all layers of the tympanic membrane subsequently became markedly hyperplastic. Disruption of the fibrous layer, invasion of keratinizing epidermis to the medial surface, and perforation were observed at three weeks. These findings indicate that tympanic membrane damage is a potentially significant aspect of the ototoxic properties of topical otic preparations.
This study was designed to investigate morphological changes in the tympanic membrane (TM) associated with cholesteatoma formation in experimental animals following application of propylene glycol to the middle ear. A 50% solution of propylene glycol was applied bilaterally to the middle ear cavities of 30 young-adult chinchillas. The animals were sacrificed for light and electron microscopic study at intervals of 2 days to 6 weeks after a single application of 0.2 ml of the propylene glycol solution. At 2 days there was complete destruction of the epidermal and mucosal layers of the TM. The denuded lateral surface rapidly became re-epithelialized by hyperplastic epidermal cells and by 2-3 weeks, keratinizing epidermis penetrated damaged areas of the fibrous layer of the lamina propria to reach the medial surface of the TM. These epidermal cells proliferated in the middle ear cavity, forming cholesteatomas. Our observations indicate that invasion of the intact, but structurally altered, tympanic membrane by hyperplastic epidermis is a primary mechanism of cholesteatoma formation in the animal model.
\s=b\ Some widely used ototopical preparations are potentially toxic to the middle and inner ear. Vasocidin Ophthalmic Solution (sulfacetamide sodium and prednisolone sodium phosphate) has been advocated as an alternative agent that may have fewer toxic side effects in the treatment of otorrhea. Vasocidin was introduced into the bullae of nine chinchillas to investigate the effects on the middle and inner ear. The organ of Corti and stria vascularis were found to be entirely normal in 17 of the 18 temporal bones studied. Changes observed in the middle ears at one week included inflammation, hemorrhage, and effusion. Examination of specimens at four weeks revealed resolution of most of the inflammatory changes. The results of this experimental study indicate that Vasocidin causes reversible middle ear inflammation with little or no toxic effect on inner ear structures. TX 75235 (Dr Brown). phate as active ingredients) has recently been suggested as an alterna¬ tive preparation for treatment of otorrhea.5 Sulfacetamide, the antibi¬ otic used in Vasocidin, is a sulfonamide antimicrobial agent that is effective against a variety of grampositive and gram-negative microor¬ ganisms.6 Neither sulfacetamide nor the antiinflammatory agent predniso¬ lone is known to have ototoxic proper¬ ties. However, the possibility of oto¬ toxic side effects resulting from topi¬ cal application of Vasocidin to the middle ear cavity has not been experi¬ mentally tested. This study was designed to assess the morphologic effects of Vasocidin on the middle and inner ears of experimental animals following its application to the tym¬ panic cavity. MATERIALS AND METHODSEighteen temporal bones from nine young-adult chinchillas were evaluated following topical administration of Vaso¬ cidin to the middle ear cavity. Each chin¬ chilla received a single, bilateral applica¬ tion of Vasocidin, which contains sulfacet¬ amide sodium (100 mg/mL) and predniso¬ lone sodium phosphate (2.5 mg/mL) in a vehicle containing sodium edetate, boric acid, poloxamer 407, and thimerosal. Under ketamine hydrochloride anesthesia, 0.5 mL of the preparation was instilled directly into the middle ear cavity through a small hole placed in the superior aspect of the bulla. This route of administration was chosen to avoid damage to the tym¬ panic membrane or ossicular chain. Fol¬ lowing Vasocidin application, the experi¬ mental animals were kept alive for periods of either one week (six chinchillas) or four weeks (three chinchillas) before they were killed for histologie study of the temporal bones. Sham-operated control animals were not included, as previous experiments have documented that this does not cause middle or inner ear damage.7At the time specimens were taken for evaluation, the chinchillas were perfused via the aorta with a mixture of 1% paraformaldehyde and 2% glutaraldehyde in 0.1 mol/L cacodylate buffer at pH 7.4. The temporal bones were then removed from the skull and the middle ear cavities were opened for preliminary examination with an operating microscope...
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.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.