Epitympanic development and mastoid pneumatization in chronic otitis media with and without cholesteatoma

Abstract

Background and Objectives: Chronic otitis media (COM) is strongly related to the degree of aeration of the middle ear and mastoid. The developmental pattern of these air cell systems can affect those of COM, especially cholesteatoma, or vice versa. We investigated several anatomical indexes representing the middle ear and mastoid air cell system to research their relationship with different types of COM. Subjects and Methods: Temporal bone computed tomography were performed on 51 patients with cholesteatoma, 50 with COM, and 50 normal subjects. Height of epitympanum, degree of mastoid pneumatization and anterior epitympanic space (AES) development were measured. AES development was classified into three categories: undeveloped, single cell and multiple cells. Anatomical index measurements were compared according to the types of COM. Results: The mean height of epitympanum was 5.12mm in cholesteatoma, 6.04 mm in COM, and 7.40 mm in normal group (p<0.05). The degree of pneumatization was 20.9%, 17.2%, and 42.2% respectively. AES was undeveloped in 65%, single cell in 33%, and multiple cells in only 2% of cholesteatoma patients. In COM and normal groups, the proportions of AES were 60%, 30%, 10% and 7%, 48%, 45% respectively (p<0.05). Comparing between attic and pars tensa types of cholesteatoma, all indexes failed to show any difference. However, there was a significant difference in height of epitympanum between affected ear (5.12 mm) and contralateral ear (5.62 mm) in cholesteatoma group. Conclusions: In patients with COM, the degree of development of epitympanum and AES are significantly lower than control group. We believe epitympanic underdevelopment may be related to the pathogenesis of COM, especially with cholesteatoma