Learning Objectives: 1.Anatomical variants of tympanic compartments and their aeration patterns are one of the relevant pathogenetic factors involved in type of cholesteatoma occurrence. 2.The isthmus blockage theory could be a condition for the epitympanic type while tubal dysfunction is mandatory for mesotympanic type of cholesteatoma since the contralateral ear abnormalities are more frequent in the last one.

Introduction: In the recent years the incidence of chronic otitis media with cholesteatoma has decreased but remain a major challenge for surgeons due to the destructive characteristic of the disease. Although the pathophysiology of the acquired cholesteatoma remains to be clearly elucidated, it is presumed to be multifactorial, as many theories have been proposed and investigated. Anatomical variants of tympanic compartments and their aeration patterns are one of the contributing factors. Retraction pocket theory is the most widely accepted but the contralateral ear in patients with cholesteatoma is less studied. The purpose of this study was to evaluate the contralateral ear in patients with cholesteatoma and to determine whether the characteristics of it differ according cholesteatoma growth patterns.

Methods: The charts of 924 operations for cholesteatoma performed from January 2000 to December 2013 at the Department of Otorhinolaryngology-Head and Neck Surgery, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj- Napoca were analyzed retrospectively. Otomicroscopy was performed on both the affected and the contralateral ear. Cholesteatoma extension was noted during surgery.

Results: The age average for patients included in the study was of 41 ± 6.5 years (95%CI [39.32–42.85]). The frequency of significant changes in the contralateral ear was 49.2 %. 6.5% of patients presented with bilateral cholesteatoma. Other abnormalities were retraction pockets (32%), perforations of the tympanic membrane (25%), serous otitis media (5%). Contralateral ear modifications were more frequent in the posterior mesotympanic type of cholesteatoma cases.

Conclusions: Lower damage of contralateral ear in posterior epitympanic type of cholesteatoma supports the isthmus blockage theory for epitympanic cholesteatoma occurrence. Long-term follow-up of the condition of contralateral ear in cholesteatoma patients is mandatory for early intervention in order to prevent progression of the disease.