Ossicular Bone Modeling in Acute Otitis Media.

BACKGROUND AND OBJECTIVE:: A number of middle ear diseases are associated with pathologic bone modeling, either formative or resorptive. As such, the pathogenesis of a sclerotic mastoid has been controversial for decades. Experimental studies on acute middle ear infection have shown progressive osteoneogenesis in the bone structures surrounding the middle ear cavity, and a few studies have reported acute changes of the ossicular chain. However, detailed qualitative and quantitative information on ossicular bone modeling dynamics has not been accounted for and is thus the purpose of this study. MATERIAL AND METHODS:: The histopathology of the middle ear bone tissue structures was studied longitudinally in a rat model of acute pneumococcal otitis media, from Days 1 to 28 postinoculation. Resorptive and formative activity was semiquantitated for the ossicles and the bone tissue structures surrounding the middle ear cavity. RESULTS:: Qualitative and semiquantitative histopathology revealed initial osteoresorption, followed by increasing apposition of new bone in the middle ear cavity. Equivalently, the ossicular chain and joints were subject to initial resorption and subsequent new bone formation, but the changes occurred were delayed and to a far lesser extent. CONCLUSION:: A single incident of acute otitis media changes the osseous structures of the middle ear, which may alter properties of ossicular chain conduction. Modeling of ossicular bone is postponed compared with the bone tissue surrounding the middle ear cavity, and to a much lesser extent. The differentiated modeling pattern suggests that ossicular bone tissue possesses biologic properties resistant to morphologic changes.