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

Objective: 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).

Methods: 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.

Results: 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.

Conclusion: 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.