The purpose of this study is to follow up the dynamics of pure tone threshold and DPOAE amplitude changes induced by
glycerol with reference to its activity in the inner ear. Selection was made among 38 patients with
Meniere's disease for those having positive
glycerol test. Pure-tone audiometry and DP-gram were performed in four series: as an initial examination before
glycerol intake, 1, 2 and 3 h after. Audiometric changes formed distinct biphasal pattern at all frequencies between 250 and 4,000 Hz. The most dynamic pure tone threshold decrease occurred during the first hour. Between the first and second hour after
glycerol ingestion there was a phase of no significant hearing changes. Further pure tone threshold decrease went on within the third hour reaching its top. Observing DPOAE changes, the highest DP amplitude growth occurred after the second and the third hour at DP-gram frequencies 2, 3 and 4 kHz. The fastest DP-amplitude increase was registered as well during the first hour after
glycerol ingestion. In 11 persons with both audiometry and DPOAE positive
glycerol test, parallel dynamics in the course of the
glycerol test was observed. Biphasal
glycerol test dynamics suggests the possibility of two mechanisms of
glycerol activity in the inner ear.