The value of multifrequency tympanometry in superior semicircular canal dehiscence

In patients with superior semicircular canal dehiscence (SSCD), an additional window is added to the oval and circular window available in inner ear. The third window may reflect the audiologic and acoustic features of the middle ear by changing the dynamic characteristics of the inner ear. The aim of this study is to obtain differential diagnostic criteria related to superior semicircular canal dehiscence in ears with superior semicircular canal dehiscence, by comparing the results of resonance frequency measurements obtained through multifrequency immitancemetry with those obtained in normal ears. Research is an analytic and prospective cohort study. It was carried out in the Otorhinolaryngology Department of Ege University Hospital. Research consisted of a total of 30 individuals between 18 and 70 years of age. 20 normal healthy individuals (40 ears) and 10 patients with SSCD (14 ears) were enrolled. Research was carried out between January 2016 and June 2016 after the ethic committee's approval was obtained. Normal healthy individuals and those with SSCD received Pure Voice Audiometry Test, VEMP Test, Multifrequency İmmitancemetry and 226 Hz İmmitancemetry Test. The mean Resonance Frequency Value obtained in normal group through multifrequency immitancemetry was found as 881.25 Hz (standard deviation 88.93). However, in superior semicircular canal dehiscence group the mean Resonance Frequency Value was 817.86 Hz (standard deviation 222.41). Consequently, the resonance frequencies were measured in normal and SSCD groups but a significant difference could not be found between them. The subjects in normal group had statistically significantly higher VEMP Amplitude Values than those in SSCD group. Statistically significant difference was observed between the VEMP Amplitude Asymmettry Ratio Values of normal subjects and the ones with bilateral SSCD. The Acoustic Reflex Threshold Values, Age Values, and Pure Voice Audiometry Values of the subjects in normal group were found statistically lower than those in SSCD group. The Resonance Frequency Values obtained through multifrequency immitancemetry were not considered as diagnostic criteria that differentiate patients with dehiscence. This study wishes to help those studies that will investigate the effects of IV resonance frequency value, which is an important part of multifrequency immitancemetry, on the diagnosis of pathologies. Key Words: superior semicircular canal dehiscence, multifrequency immitancemetry, resonance frequency