Glycerol effect for endolymphatic hydrops is well known as an improvement in pure tone threshold at three hours after glycerol administration. However, a long time effect of glycerol is unknown. In this study, audiometric tests were administered during ten hours after glycerol administration in order to determine the long time effect of glycerol in cases of Meniere's disease, sudden deafness and normal subjects.
The following results were obtained;
1) The long time effect including rebound phenomenon of glycerol in the pure tone threshold did not appear in cases of sudden deafness and normal subjects.
2) The long time effect of glycerol in the pure tone threshold was observed only in cases of Meniere's disease and it was classified into the following four types, “descending type”, “descending and ascending type”, “ascending type” and “unchanged type”.
3) In the classification of audiometric types, the crest type and rising type were mainly occupied by “descending type” and “descending and ascending type” and the falling type was mainly occupied by “ascending type”.
4) The half of Meniere's disease showed rebound phenomenon in the pure tone threshold.