Peak Width in Multifrequency Tympanometry and Endolymphatic Hydrops Revealed by Magnetic Resonance Imaging

Abstract

To investigate the relationship between the peak width of the characteristic "M"-shaped peak of 2 kHz conductance tympanometry and the degree of endolymphatic hydrops in magnetic resonance imaging (MRI) after intratympanic or intravenous gadolinium administration. Prospective study. An academic university hospital. One hundred twenty-eight ears in which multifrequency tympanometry was performed and endolymphatic space size was evaluated by MRI. Forty-five patients were examined bilaterally and 38 patients were examined unilaterally. Endolymphatic space size was evaluated by MRI after intratympanic or intravenous gadolinium injection. Endolymphatic space size was classified into three groups: none, mild, and significant in the cochlea and in the vestibule. The relationship between the degree of endolymphatic hydrops and peak width of 2 kHz conductance tympanometry was investigated. The peak width in 94 ears in which significant endolymphatic hydrops was observed on MRI in the cochlea and/or the vestibule was 178.8 ± 102.7 daPa. The peak width in 21 ears in which mild but not significant endolymphatic hydrops was observed on MRI in the cochlea and/or the vestibule was 126.0 ± 77.1 daPa. The peak width in 13 ears with no endolymphatic hydrops in the cochlea and vestibule was 107.1 ± 84.1 daPa. The peak width in ears with significant endolymphatic hydrops was larger than that observed in ears with no endolymphatic hydrops. However, the peak width was not significantly different between cases of mild and absent endolymphatic hydrops. Large peak width in multifrequency tympanometry was associated with significant endolymphatic hydrops.