Evaluation of resonance frequency di̇fferences with glycerol test in meneres disease

AIM: Evaluate the resonance frequency values by forming dehidration effect in the inner ear by glycerol test which is used as a diagnostic method in Meniere's Disease (MD). MATERIAL AND METHODS: Twenty Meniere's disease patients over 19 years of age (20 affected ears, 20 control ears)wo meet the criteria were admitted to the Ear Nose Throat (ENT) Department of Baskent University. Pure-tone hearing levels (125-8000 kHz), pure-tone mean values, and multifrequency tympanometry with resonant frequency (RF) tests were performed. RF values of 50 healthy persons were compared between affected and control ears. Pure-tone thresholds and RF values were compared between only MH ears before and at 1, 2 and 3 hours after administration of glycerol 1g/kg. RESULTS: The mean age of the 20 patients was 47.25 ± 10.5, 9 women (45%) and 11 men (55%). Average RF values in healthy ears were 979.41 ± 156.26 Hz, in affected ears 808.0 ± 410.09 Hz, and in control ears 972.5 ± 499.07 Hz before glycerol intake. There was a significant difference between the RF values between the affected ears and healthy ears before the glycerol intake (p = 0.047). When RF values were compared of affected ears, average RF values decreased to 748.0 ± 402.1 Hz to 808.0 ± 410.1 Hz at the first hour of glycerol intake, and this value increased at the following hours. Statistically significantdifferences were obtained between RF values, 1 hour before and after glycerol intake(p = 0.030). However, in the affected ears, there was no statistically significant difference between the pure-tone levels before and one hour after glycerol intake, but a significant decrease in hearing thresholds at 125, 250, 500 and 1000 Hz at 3 h (p = 0.000, p = 0.000, p = 0.000, p = 0.000, respectively). CONCLUSION: We observed decreased RF values when we expected to reach to normal ear values with dehydration effect. According to these results, we suggest that MH has different inner ear dynamics and the normal RF values of MD are different from the healthy ears. Also, we think that the decrease of the inner ear pressure causes the reduction of the mass effect and the stiffness effect on the anulus ligament. Thus, RF reach the normal values (between attacks). Changes in RF values with glycerol test are observed at 1 hour. KEY WORDS: Meniere's Disease, Multifrequency tympanometry, Resonance frequency, glycerol test, middle and inner ear mechanics.