Otosclerosis is one of the main causes of deafness in adults, characterized by primary osteodystrophy of the otic capsule and sensorineural hearing loss. Even though Computed Tomography (CT) is the exam of choice, the findings can be subtle, since knowledge of radiological patterns can avoid underdiagnosis. Starting from patients with compatible clinics, a survey of the epidemiological and radiological behavior was carried out in a Brazilian public health institution, comparing it with available literature data, aiming to increase diagnostic accuracy. A total of 31 patients with compatible clinical and tomographic findings were selected, and all images and corresponding reports were reviewed. As otosclerosis was clinically suspected in both mastoids of the 31 individuals studied, even if the CT evidence was only unilateral, both petrosal bones (62 in total) were included. Parameters such as age, sex and laterality were evaluated.
The disease was graded using the Symons and Fanning Classification: grade 1, exclusively fenestral; grade 2, patchy localized cochlear disease, with or without fenestral involvement, and extension to the basal cochlear gyrus or middle/apical gyrus or both basal and middle/apical gyri; grade 3, diffuse confluent cochlear involvement with or without fenestral involvement.
There was a higher prevalence in females (65%), in addition to bilateral involvement (54%) and in patients in the 4th decade of life (36%), followed by patients in the 5th decade (23%) and 3rd decade (19%).
Of the 62 CT scans evaluated, 48 had findings of primary osteodystrophy of the otic capsule, with grade 1 otosclerosis being the most common (62%), followed by grade 2 (24%) and, less common, grade 3 (12%). Such data are consistent with current literature.
Considering that the findings of otosclerosis may be tenuous, despite clinically compatible, the study of the epidemiological and radiological profile proves to be a useful tool to improve diagnostic accuracy.