Evaluation of Midle Ear Space Using a Temporal Bone CT

Abstract

The dimensions of the supratubal recess, epitympanum and mastoid peumatization were measured on 182 semiaxial computed tomograms of 123 cases.
The measurement was done by using Image Command 5098 at one slice (1.5mm) lower level than at the level of geniculate ganglion. The temporal bones were classified into six types; simple otitis media type, attic retraction type with or without cholesteatoma, tensa adhesive type with or without cholesteatoma, and normal type.
The dimensions of the supratubal recess and epitympanum were significantly correlated with that of mastoid pneumatization. The dimensions of the epitympanum in simple otitis media type and tensa adhesive type were significantly larger than those of the other types.
The supratubal recess in normal type was significantly larger than that of other types. Significant difference was not recognized between the supratubal recess of tensa adhesive type with cholesteatoma and without cholesteatoma. But the supratubal recess of attic retraction type with cholesteatoma was significantly smaller than that without cholesteatoma. It was suggested that the dimension of the supratubal recess should be one of the important pathogenetic factors of attic cholesteatoma.