Learning Objectives: To investigate the cholesteatoma growth pattern and location of TM retraction in the CLE of patients with acquired middle ear cholesteatoma.

Introduction: Theories of acquired cholesteatoma pathogenesis involving previous tympanic membrane (TM) retraction are the most widely accepted. Since prospective studies are very difficult to perform, the study of the contralateral ear (CLE) in patients with cholesteatoma seems to be a good alternative to understand its pathogenesis. Our previous studies had demonstrated that TM retraction is the main alteration in the CLE of patients with cholesteatoma. We now propose to analyze these alterations in greater detail and correlate the observations with the cholesteatoma growth pattern in the main ear.

Methods: Our cross-sectional study included 242 consecutive patients diagnosed with posterior epitympanic (PEC) or posterior mesotympanic cholesteatoma (PMC) in at least one ear between August 2000 and March 2013. The patients had no surgical history. We performed videotoscopy in both ears and analyzed the videos independently in a blind manner. The prevalence of PEC and PMC and moderate-to-severe pars tensa and flaccida retractions in the CLE was evaluated. The observed alterations in the CLE were compared with the cholesteatoma growth patterns in the main ear.

Results: Cholesteatoma and TM retraction were observed in 17.8% and 42.6% of the CLEs, respectively. In instances where the primary ears displayed PEC or PMC, identical cholesteatoma growth pattern was observed in 89.5% and 64% of the CLEs, respectively (p < 0.0001). A similar phenomenon was observed in cases of pars tensa and flaccida retraction (p < 0.0001).

Conclusion: Patients with cholesteatoma have a greater probability of having both cholesteatoma and TM retraction at the same site in the CLE. Our findings validate the hypothesis that cholesteatoma pathogenesis is associated to previous TM retraction, with a high prevalence of bilaterality.