Otosclerosis: incidence of positive findings on high-resolution computed tomography and their correlation to audiological test data.

OBJECTIVES

Computed tomographic (CT) scanning with slices of 1 mm or more has not been sufficient to demonstrate otosclerotic foci in most cases to date.

METHODS

We investigated the validity of CT scans with a 0.5-mm cubical scan technique, with and without planar reconstruction, and correlated these findings with audiological data. Forty-four temporal bone CT scans from 30 patients with conductive or mixed hearing loss were evaluated.

RESULTS

Otosclerotic foci were visualized in 74% of the cases. With reconstruction at the workstation, the sensitivity increased to 85%. Whereas in fenestral otosclerosis a correlation was found between the size of the focus and the air-bone gap, no correlation was seen between the size of the focus and bone conduction thresholds with cochlear involvement. Otosclerotic foci in patients treated with sodium fluoride were smaller than those in patients without treatment. This finding may indicate a beneficial effect of sodium fluoride on otosclerotic growth.

CONCLUSIONS

High-resolution CT scans are a valid tool that can be used to confirm, localize, and determine the size of clinically suspected otosclerotic foci.