Electrocochleographic changes in endolymphatic hydrops induced by type II collagen immunization through the...

Changes in action potential (AP) and summating potential (SP) were investigated in guinea pigs immunized with type II collagen through the stylomastoid foramen. Endolymphatic hydrops could be induced in four of 11 guinea pigs. The striking feature of the electrocochleographic waveform in guinea pigs with endolymphatic hydrops was the negative SP recording in response to high frequency tone bursts. Furthermore, abnormal changes in AP were observed in three of four hydropic guinea pigs. Morphologic study of the cochleas in these three guinea pigs with light microscopy revealed spiral ganglion cell degeneration in addition to endolymphatic hydrops and almost normal sensory hair cells. These results suggest that guinea pigs with hydrops as produced by our procedure can serve as a useful model of Meniere's disease, that autoimmune response may play an important role in the etiopathogenesis of Meniere's disease, and that spiral ganglion cell degeneration together with endolymphatic hydrops seems to contribute to abnormal changes in AP.