CT findings of automastoidectomy

ABSTRACT

Cholesteatoma of the middle ear and mastoid sometimes destroys the posterior wall of the external auditory canal(EAC), and this phenomenon is termed as "automastoidectomy". During the past two years the authors reviewed the CT features of automastoidectomy in eight patients with middle ear cholesteatoma. There was a variable amount of the cholesteatomatous mass or debris within the mastoid cavity in all patients, of whom air collection was found in four. Interestingly, the site and pattern of the erosion of the EAC were nearly, identical between patients with air in the mastoid cavity and those without it . Air in the mastiod cavity was the only clue of the expulsion of the cholesteatoma. So, we think that the expulsion of the cholesteatoma might be predicted when the erosion of the EAC is present in patients with cholesteatoma in the mastoid cavity. CT clearly depicted associated complications caused by the cholesteatoma, such as ossicular destruction (n=8), the eroion of the facial nerve canal (n=2), the erosion of the lateral semicircular canal (n=2), the erosion of the tegmen (n=1), the erosion of the sigmoid sinus plate(n=1), the erosion of the superior esmicircular canal (n=1), and the erosion of the vestibule (n=1). Although much of the natural history of the middle ear cholesteatoma still remains to be determined, we think that careful evaluation of one type of possible progression of the disease will help us understand its clinical course. Moreover, our findings strongly support the use of CT for evaluation of "automustetomy" seen in many cases of cholesteatoma.es of cholesteatoma.