Measurement of action potential thresholds in experimental endolymphatic hydrops.

Unilateral experimental endolymphatic hydrops was created by endolymphatic sac and duct obstruction in guinea pigs. Studies of action potential (AP) threshold were then performed and compared with histologic findings. Action potential thresholds were significantly increased in the hydrops ears. The close relationship between AP changes and hydrops was sufficient to allow the detection of hydrops by AP threshold measurements alone. The AP threshold changes were positively related to the degree of hydrops and postoperative interval in a manner consistent with hearing changes seen in Meniere's disease. Based upon the foregoing, experimental endolymphatic hydrops appears to be a valid and usable model for the study of the cochlear aspects of Meniere's disease.