[Experimental endolymphatic hydrops and its related morphological and functional changes in guinea pigs].

The endolymphatic hydrops was induced successfully in 13 guinea pigs by blocking the endolymphatic duct and sac, and the morphological and functional alterations (especially on semicircular canal function) after hydrops were studied by means of ENG, EcochG and serial section techniques. Hydrops in the cochlear duct was evident in the apical and/or near apical turns, especially in earlier stages. Dilation of the saccule was seen in all samples, but was barely noticeable in the utricle and semicircular canal's endolymphatic space. Degeneration in the corti's apparatus, stria vasculi and spiral ganglion occurred late. No evident changes of the sensory components in the saccule, utricle and semicircular canals were seen under the light microscope. The hearing loss in earlier stages of hydrops was evident at lower frequencies: later stages showed effects at all frequencies. The cochlear recruitment and fluctuation phenomena were observed in a few of the operated animals. The value of -SP/CAP in a few animals was significantly after operation. The functional changes of semicircular canals were demonstrated by the semicircular paralysis (CP), directional preponderance (DP), vestibular recruitment (VR) and elevated threshold of nystagmus to angular acceleration stimuli. There was no significant correlation between the degrees of hearing loss and impaired semicircular function. The criteria of ENG elicited by the quantitative angular acceleration stimuli for evaluating the semicircular canal function in guinea pigs is proposed for the first time in our experiment.