Learning Objectives:

Introduction: Patients with significant endolymphatic hydrops (EH) sometimes show a connection between the footplate and the dilated saccule. It was supposed that this connection might cause the low-frequency air-bone gap in Menière's disease. The purpose of this study was to investigate the effects of significant EH showing a footplate-saccule connection on hearing, particularly for low-frequency air-bone gaps.

Methods: Evaluations were conducted using 1996 ears, evaluated by 3-T MRI performed 4 ;h after intravenous injection of Gd. The degree of EH in the vestibule and cochlea was classified into three grades: none; mild; or significant. Findings of the connection were checked. Ninety-one ears showed the connection. After elimination of ears with middle or inner ear abnormalities and severe hearing loss, 60 ears with the connection were evaluated. We selected those patients who had one ear with the connection and the other with significant EH of the vestibule and/or cochlea without the connection. Hearing between each ear was then compared using the t test.

Results: Significant differences between ears with the connection and ears with significant EH of the vestibule and/or cochlea without the connection were seen for air-bone gap at 250 ;Hz and 3 pure-tone averages (500-, 1000- and 2000-Hz thresholds). Low-frequency air-bone gaps improved after EH medication in some patients.

Conclusions: Ears with significant EH that show a footplate-saccule connection are associated with not only sensorineural hearing impairment, but also low-frequency air-bone gap. Changes in low-frequency air-bone gaps might reflect this aspect of EH.