The Validity of Computed Tomography in Complicated Chronic Otitis Media

Background/ We assessed the validity of computed tomography (CT) in the diagnosis of complicated chronic otitis media (COM). Patients and The findings obtained from a pre-operative high resolution CT of temporal bone including coronal and axial views of 20 patients with complicated COM were compared to their intraoperative findings. In our study, CT was helpful in determining the anatomy of the mastoid and could accurately predict the mastoid air cell aeration, size and status of ossicles, presence of lateral semicirculal canal (SCC) fistula and post-auricular fistula (All sensitivities equal to 100%). But it overdiagnosed the erosion of tegmen (positive predictive value of 50%). CT was unable to distinguish between cholesteatoma and fluid (abscess or effusion) and granulation tissue or polyps and was also unable to correctly reveal the facial nerve dehiscence and had a low sensitivity for showing erosion of facial canal (50%) and sigmoid sinus (60%). Because most complications resulting from cholesteatoma are caused by bony erosions, CT is helpful in determining the complications of COM. CT can accurately predict the extent of disease and is helpful in detection of some complications such as fistula of Lateral Semicircular Canal (LSC), erosions of dural plate and ossicular erosions. However, it is unable to distinguish between cholesteatoma, mucosal disease and fluid, and little it did contribute to detecting the facial nerve course and dehiscence. It cannot also be used for the diagnosis of the sigmoid sinus problems which could be related to no contrast administration in our study.