Electrophysiological Aspects of Surgically-Induced Endolymphatic Hydrops

Endolymphatic hydrops, a characteristic finding in Meniere’s disease can be induced in guinea pigs by surgical obliteration of the endolymphatic duct and sac. Since the reports by Harada [1], Naito [2], and Kimura [3], this hydropic animal has frequently been used as an animal model of Meniere’s disease. The purpose of the present paper is to summarize the results of our 10-year study on these animals [4–9] and to review the recently published articles by other investigators. In the present study, endolymphatic hydrops was induced in 136 albino guinea pigs by obliterating the endolymphatic duct and sac. The presence of the hydrops was histologically confirmed in a majority of the cases (Fig. 5.1). The endolymphatic potential (EP) was recorded through the round window and the recording electrode for other cochlear potentials was placed at the round window. The sound stimuli were clicks generated by a 90 μs rectangular pulse and tone bursts of 0.5–16 kHz with a 1 ms rise-fall time and a 10 ms duration. Similar methods were used in the majority of the reports reviewed in the present paper. Therefore, the methods or the conditions of the experiments used elsewhere will be described only when they differ from ours.