CT evaluation of the anterior epitympanic recess. Comparison among non-inflammatory ear, chronic otitis media with central perforation and cholesteatoma.

The structures of the anterior epitympanic recess and its surrounding tissues were examined among non-inflammatory ear, chronic otitis media with central perforation and cholesteatoma, using axial scans of high resolution computed tomography. The length and width of the recess, as well as the number of the slices where the cog was determined, had no significant differences among them. Thus, the bony structure of the recess was considered to be seldom influenced by inflammatory processes. In the non-inflammatory ear, the degree of pneumatization around the recess was similar to that of the petrous apex cells and lower than that of the mastoid cells. In the chronic otitis media with central perforation and cholesteatoma, the pneumatization of the whole temporal bones was suppressed and the tendency was also found that the cells around the recess were less pneumatized than the mastoid cells. When cholesteatoma invaded into the anterior epitympanic recess, the destruction of the bony protrusion of the lateral wall between the recess and the epitympanum was recognized, as well as the disappearance of the cog. The bony protrusion was considered to be an inferior extension of the cog toward the anterior tympanic spine.