QUANTITATIVE ANALYSIS OF CHOLESTEATOMA USING HIGH RESOLUTION COMPUTED TOMOGRAPHY SHIGERU KIKUCHI, M. D. and TATSUYA YAMASOBA, M. D. Department of Otolaryngology, Kameda General Hospital, Kamogawa TOSHITAKA IINUMA, M. D. Department of Otolaryngology, Tokyo University Branch Hospital, Tokyo Seventy-three cases of adult cholesteatoma, including 52 cases with pars flaccida type cholesteatoma and 21 with pars tensa type cholesteatoma, were examined using high resolution computed tomography, in both axial (lateral semicircular canal plane) and coronal sections (cochlear, vestibular and antral plane). These cases were classified into two subtypes according with the presence of extension of cholesteatoma into the antrum. Sixty cases with chronic otitis media with central perforation (COM) were also examined as controls. The various locations of the middle ear cavity were measured in term of size with comparisons among pars flaccida type cholesteatoma, pars tensa type cholesteatoma and COM. The results were as follows: 1) The width of the attic was significantly larger in both pars flaccida type and pars tensa type cholesteatoma than in COM. 2) With pars flaccida type cholesteatoma there was a significantly larger distance between the malleus and lateral wall of the attic than with COM. In contrast, the distance between the malleus and medial wall of the attic was significantly larger with pars tensa type cholesteatoma than with COM. 3) With cholesteatoma extending into the antrum, regardless of the type of cholesteatoma, there were significantly larger distances than with COM at the following sites; the width and height of the aditus ad antrum, and the width, height and anterior-posterior diameter of the antrum. However, these distances were not significantly different between cholesteatoma without extension into the antrum and COM. The hitherto demonstrated qualitative impressions of bone destruction in cholesteatoma were quantitatively verified in detail using high resolution computed tomography. Key words:

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