Pathogenesis of attic retraction pocket and cholesteatoma as studied by computed tomography.

It is hypothesized that blockade of the tympanic isthmus causes isolation of the attic and the adjacent middle ear spaces and that subsequent building up of the negative pressure in these spaces results in retraction of the pars flaccida, leading to formation of attic retraction pockets and cholesteatomas. To examine this theory, computerized tomographic (CT) findings of these conditions were evaluated in a series of 53 ears with retractions of the pars flaccida (attic retractions of Tos type II or deeper), including both retraction pockets and cholesteatomas. In 26 of 28 ears with attic retraction pockets, at least a portion of attic was aerated, and in 22 of these 26 ears, the mastoid antrum was also aerated