Sweep Frequency Impedance Measures of Otosclerosis

This study aimed to validate the preoperative diagnosis of otosclerosis using a Sweep Frequency Impedance (SFI) meter. In addition, it investigated whether the measurement values obtained from the SFI meter correlate with the perceived stiffness of the stapes footplate.

Retrospective cohort study.

A tertiary referral center.

Thirty-seven ears were surgically confirmed between September 2020 and December 2023 at Kanazawa University Hospital and affiliated institutions-22 diagnosed with otosclerosis and 15 with ossicular discontinuity.

(1) The diagnostic performance of SFI, tympanometry, the Carhart notch, and CT demineralization imaging. (2) Evaluation of the correlation between stapes footplate stiffness and SFI meter parameters, specifically the change in sound pressure level (ΔSPL) and the resonance frequency (RF).

Correct diagnosis rate of SFI. Correlation between preoperative audiometric data and SFI meter parameters (ΔSPL and RF). Correlation between preoperative hearing data and the perceived stiffness of the stapes footplate.

The SFI meter demonstrated the highest diagnostic accuracy, with a correct diagnosis rate of 0.91, followed by the Carhart notch at 0.73 and CT imaging and tympanometry at 0.459. No statistically significant correlations were observed between preoperative audiometric data and SFI meter parameters or the perceived stiffness of the stapes footplate.

The findings suggest that the SFI meter may provide superior diagnostic accuracy compared with conventional testing modalities. Although no statistically significant correlations were identified, the direction of the observed associations was consistent with the expected biomechanical model, in which increased stiffness would be associated with higher resonance frequency, reduced SPL modulation, and a larger AB gap. SFI measurements may offer a means to estimate the degree of stapes footplate fixation preoperatively.