Electrocochleography in the diagnosis of delayed endolymphatic hydrops.

It is known that delayed endolymphatic hydrops (DEH) occurs in patients with unilateral and/or bilateral profound hearing loss. In the ipsilateral and bilateral types of DEH, no audiological tests can be performed on the affected ear because of profound deafness, although these tests can be done in the contralateral type. Electrocochleography (ECochG) was recorded on better hearing ears in both types of DEH. The results showed an increased negative summating potential (SP) in 6 out of 10 contralateral DEH patients whereas it could be measured in only one of 10 ipsilateral DEH patients. The mean SP/AP ratio of the contralateral type was 0.42 which was significantly larger than that of the ipsilateral type. The results suggest that contralateral-type DEH has the same pathology in the cochlea as Meniere's disease, and that ECochG can distinguish between these two types of DEH.