[Effectiveness of computed tomography in the diagnosis of otosclerosis]

Computer-aided tomography (CAT) is the most informative method for imaging the morphologic substrate of an otosclerotic process. In otospongiosis the tomograms show compact bone demineralization sites to the front of the vestibule fenestra (the fenestral form) or round the cochlear osseous capsule (the cochlear form); this latter form is better detectable by densitometry. During the stage of "mature" inactive otosclerosis the labyrynth fenestra are exposed to partial or complete obliteration. Combinations of active and inactive foci in the temporal bone pyramid are seen in 38% of cases. CAT helps accurately define the cause of stapedoplasty failure: anvil necrosis and the prosthesis subdislocation. CAT should be an obligatory diagnostic component in examinations of patients with sound conduction abnormalities.