Effects of Glycerol Test on Resonance Frequency in Patients with Ménière's Disease

To evaluate resonance frequency (RF) values via dehydration effects in the inner ear caused by the glycerol test, which is used as a diagnostic method for Ménière's disease (MD).

Twenty adult patients with unilateral MD were included in the study. Before, and then at 1, 2, and 3 h after administration of glycerol (1 g/kg), pure-tone hearing levels (125-8,000 kHz) and multifrequency tympanometry tests were performed. As a control, the RF values of the ears of 25 healthy subjects (i.e., 50 ears) were compared to the affected and unaffected ears in the 20 MD patients.

There was a significant difference between the RF values of affected and healthy ears before glycerol administration (p = 0.047). The RF values before and after glycerol administration into affected ears were compared. The average RF values decreased significantly from 748.0 ± 402.1 to 808.0 ± 410.1 Hz at 1 h after glycerol intake, and this value increased during the subsequent hours. There were no statistically significant differences between the pure-tone levels before and 1 h after glycerol administration, but a significant decrease was observed at 3 h.

We suggest that MD has different inner-ear dynamics and normal RF values when compared to healthy ears. Furthermore, decreased inner ear pressure causes reduction of the mass effect and a stiffening of the annular ligament. We conclude that pre- and post-RF tests should be added to the test battery for diagnosis of MD.