Multifrequency multicomponent tympanometry in normal and otosclerotic ears

A multifrequency multicomponent admittance meter was used to evaluate 70 ears of patients affected by fenestral otosclerosis (Os ears), monolateral (16 cases) or bilateral (27 cases). The 16 contralateral ears of the patients with monolateral otosclerosis who presented a pure-tone air-bone gap less than 10 dB were evaluated separately (Cos ears). A group of 48 ears belonging to 24 otologically normal subjects (N ears), with hearing thresholds better than or equal to 10 dB HL in the frequencies between 250 and 8000 Hz served as a control group. The purpose of the study was to evaluate the acoustic admittance characteristics of the three groups of ears, with particular regard to the parameters represented by the resonance frequency (RF), the acoustic conductance value (G) at RF and the individual interaural differences in these two parameters in the N and Cos groups. The degree to which fenestral otosclerosis can influence variations of RF and the correlation between the value of RF and conductive hearing loss in patients with clinically confirmed pictures and in the controlateral ears in the cases where the disease was clinically unilateral were also investigated. The study reveals statistically significant differences between the RF means in the N group (1085 ± 244 Hz) vs the Os group (1264 ± 320 Hz) (p < 0.001) and between the G means in the N group (5.33 ± 1.72 mmhos) vs the Os group (4.46 ± 2.54 mmhos) (p = 0.04) and N group vs Cos group (3.42 ± 2.27 mmhos) (p < 0.001). No correlation was found between the value of RF and conductive hearing loss. This study also shows how prognostic value may also be attributed to conductance at middle-ear pressure balancement: extremely low values for this parameter at RF are indicative of initial otosclerotic involvement of the oval window.