Abstract
Endolymphatic hydrops was induced in the left ear of 10 albino guinea pigs by obliterating the endolymphatic duct and sac, and the effect of isosorbide was examined. DPOAEs at 4, 6 and 8 kHz were measured three times, ie before surgery, one to two weeks after surgery and one to two hours after oral administration of isosorbide. DPOAEs recorded one to two weeks after surgery exhibited a significant reduction in amplitude at 4 and 6 kHz, while there was no change at 8 kHz. According to our previous study, this finding indicates that the induced hydrops is still in the early stage where the threshold of the compound action potential has not yet elevated. Oral administration of isosorbide restored the amplitude of DPOAEs to the preoperative level at 4 and 6 kHz. The results obtained in the present study indicates that isosorbide is quite effective in preventing the development of hearing loss in the early stage of hydrops.
