Using surgical observations of ossicular erosion patterns to characterize cholesteatoma growth.

OBJECTIVE To describe and quantify growth patterns of cholesteatomas within the middle ear using a scaled rating system that characterizes patterns of ossicular erosion. STUDY DESIGN Retrospective case review. SETTING Tertiary referral center. PATIENTS Patients undergoing first-time surgery for primary and secondary acquired cholesteatomas. INTERVENTIONS Intraoperative assessments of ossicular destruction by cholesteatoma growth were performed. MAIN OUTCOME MEASURES A scaled system was created to classify the degree of erosion for each ossicle. Ossicular destruction patterns were quantified and compared. RESULTS A total of 157 ears of 152 patients with cholesteatomas, who met our inclusion criteria, were operated on by the senior author (S.H.S.) between 1992 and 2009. The incus was the most significantly affected ossicle, whereas the stapes was the most variably affected ossicle. The most commonly represented ossicular erosion patterns for primary acquired cholesteatomas demonstrated an intact malleus abutting cholesteatoma, erosion of the incus, and minimal stapes involvement, whereas the common erosion patterns for secondary acquired cholesteatomas demonstrated intact malleus abutting cholesteatoma, erosion of the incus, and erosion of the stapes. CONCLUSION Previous assessments of ossicular destruction by cholesteatomas were largely created for staging purposes and for guiding surgical reconstruction. Minimal information can be obtained from these data that both describe and quantify cholesteatoma growth patterns. Our ossicle categories more completely described how erosion develops using a scaled system. Common erosion patterns for both primary acquired and secondary acquired cholesteatomas validate anatomic studies and observations of how middle ear anatomy and compartment boundaries guide cholesteatoma growth.