Wideband frequency impedance for diagnosis of ossicular chain abnormality.

ABSTRACT

BACKGROUND: The accurate estimation of the ossicular chain abnormalities using existing functional examinations has been difficult. AIMS/OBJECTIVES: This study aimed to verify the accuracy of preoperative diagnosis of ossicular chain abnormalities using a wideband frequency impedance (WFI) meter, which can measure the dynamic characteristics of the middle ear. MATERIAL AND METHODS: Retrospective cohort study. Fourteen ears of patients with ossicular chain abnormalities that were definitively diagnosed surgically were included in this study. The following data were collected for each participant sound pressure level (SPL) curve measured using the WFI meter and a sweep frequency impedance (SFI) meter, WFI measurements plotted on the resonance frequency (RF)-ΔSPL plane, distribution map of the dynamic characteristics of the middle ear, preoperative audiometry results, and the definitive surgical diagnosis. RESULTS: The SPL curve obtained using the WFI meter had lesser noise than that obtained using the SFI meter. The distribution map revealed that the ossicular chain separation range and ossicular chain fixation range were completely separated. The hearing data tended to be poor in cases with small ΔSPL. CONCLUSIONS AND SIGNIFICANCE: WFI can potentially enhance the accuracy of SFI. In addition, it can also be used for the classification of ossicular chain separation and fixation as well as the quantification of fixation in cases of ossicular chain anomalies that cannot be diagnosed using conventional tests.