[Evaluation of glycerol test in Meniere's disease with pure tone audiometry and distortion product otoacoustic emission].

The purpose of the work was to follow up changes in the pure tone audiometry and distortion products otoacoustic emissions (DPOAE) after glycerol administration in Meniere's patients. Twenty patients with Meniere's disease and 16 with cochlear hearing loss without vestibular symptoms were subjected to the glycerol test following the complete audiological evaluation. Glycerol was administered orally 1.5 ml/kg of body weight dissolved in the equal amount of the physiological saline. The results of the glycerol test were analyzed with reference to changes in the pure tone threshold and DPOAE testing. Both investigations were performed in four series: as an initial testing before the glycerol intake and next--one, two and three hours after the glycerol administration. DPOAE included DP-gram registration (L1 = L2 = 70 dB; f2/f1 = 1.22; 1/2 octave) and input/output (I/O) function at 2, 4 and 6 kHz. The glycerol test was regarded as positive in the audiometry if the pure tone threshold improved at least 15 dB at minimum 3 frequencies. Positive result of the glycerol test in DPOAE was judged if DP amplitude increased more than 5dB at 2 or more frequencies in DP-gram and/or DP-threshold lowered at least 10dB in minimum two I/O registrations. In the subjects with Meniere's disease, 11 positive and 9 negative glycerol tests in audiometry and 10 positive and 10 negative DPOAE glycerol tests were obtained. In the reference group, one audiometric glycerol test and two DPOAE glycerol tests were regarded as positive. Much conformity, making 85%, between audiometric and DPOAE tests results is observed. The dynamics of the parameter changing in the consecutive test hours was also similar in both pure tone audiometry and DPOAE. These studies suggest that distortion product otoacoustic emission could be useful in diagnostics of Meniere's disease and would be a valuable diagnostic tool as an objective examination.