PATHOGENESIS OF MIDDLE-EAR ADHESIONS

Middle ear adhesions are well-known to the ear surgeon, although data on etiology, pathogenesis, and significance are lacking in current lit erature, This study on experimental acute otitis media presents histop athological data on these aspects. Pneumococci were inoculated in the right middle ear bulla of 25 rats; the left ear served as control, At days 4, 8, 16, 90, and 180, respectively, 5 rats were decapitated, and the bullae were removed, opened, and stained with periodic acid-Schif f (PAS)/alcian blue. The entire middle ear mucosae were dissected from the bone, embedded as whole mounts in colophonium chambers, and exami ned by light microscopy. Representative parts of the mucosae were sect ioned and examined in the same way, All inoculated ears from day 8 and later (20 in total), contained mucosal adhesions of various sizes, sh apes, and locations. None were found in control ears, The site of pred ilection for the development of adhesions was the hypotympanum, follow ed by the anterior epitympanum, the attic, the drum, the interossicula r spaces, and the tubal orifice, Based on present histopathological fi ndings, we conclude that the middle ear adhesion is a pathological phe nomenon caused by infection, and we propose a six-stage hypothesis of pathogenesis: 1. Localized epithelial rupture; 2. Prolapse of subepith elial tissue; 3. Epithelialization of the prolapse, resulting in a pol ypous/fold-like prominence; 4. Growth and elongation of the prominence ; 5. Fusion of the end/tip of the prominence with another part of the mucosa; 6. Formation of an adhesion.