Dynamic hearing thresholds after glycerol ingestion may be modified by endolymphatic hydrops status in Ménière's disease.

Endolymphatic hydrops (ELH) can be identified by electrophysiological and radiological examinations. We aimed to investigate the relationship between audiometric glycerol test and delayed magnetic resonance imaging (MRI) of the inner ear after intratympanic gadolinium in patients with unilateral Ménière's disease (MD). Forty-two patients with unilateral definite MD underwent audiometric glycerol test and delayed MRI following intratympanic gadolinium application. The degree of cochlear ELH was moderately positively correlated with the mean hearing threshold below 2 kHz. For those ears with positive glycerol results, the best hearing threshold was measured at 3 h and the maximal improvement of hearing threshold was observed within the third hour. The overall positive rates of glycerol test did not differ between ELH (+) and ELH (-) subgroups based on the MRI findings. Significant temporal changes in the positive rate were only observed in the ELH (+) subgroup. The rebound rate did not change significantly over time in either subgroup. In MD patients, glycerol-induced dynamic shift of hearing threshold may be modified by the hydropic status of the inner ear. For those without radiological ELH, glycerol test could be used as additional diagnostic tool to detect hydrops.