Otosclerosis: Incidence of positive findings on temporal bone computed tomography (TBCT) and audiometric correlation in Korean patients

Objective

To assess the incidence of otosclerotic foci identified by temporal bone computed tomography (TBCT) in Korean and to determine the correlation between the extent of otosclerotic foci and audiometric findings.

Methods

Thirty-one patients (37 ears) who were surgically confirmed otosclerosis and underwent preoperative TBCT scan were included. Patients underwent pre- and postoperative audiometric evaluation and TBCT. The mean air conduction (AC) thresholds and bone conduction (BC) thresholds, air–bone gap (ABG), and the difference between pre- and postoperative ABGs were determined. Otosclerotic foci were identified by the presence of hypodense lesions near the fissula ante fenestram and the otic capsule in the TBCT. The areas with hypodense lesions and the density ratio of the otosclerotic foci were compared by pre- and postoperative audiometric parameters.

Results

Hypodense lesions were identified by the TBCT in 27 out of 37 cases (73%). Fenestral types were found in 23 cases and combined fenestral and cochlear types in 4 cases. There was a significant correlation between the density ratio of the otospongiotic foci and the postoperative mean ABG (P = 0.03). However, there was no correlation between the size of the hypodense area and any of the audiometric parameters tested (P > 0.05).

Conclusion

The rate of positive TBCT findings for otosclerosis in our series was 73%. The extent of the hypodense lesion did not correlate with the preoperative hearing levels. However, the density ratio of the hypodense lesion influenced the surgical outcomes.