Electrocochleographic changes in relation to cochlear histopathology in experimental endolymphatic hydrops.
The relation between electrocochleographic and histological changes in experimental endolymphatic hydrops was studied 1, 2, 4, or 8 months after obliteration of the endolymphatic sac. An increase in the compound Action Potential (AP) threshold was found 2, 4, and 8 months after obliteration. This increase was strongly correlated with loss of outer hair cells, nerve fibres and spiral ganglion cells. An enhanced negative Summating Potential (SP) and an enhanced SP-AP ratio were found mainly in animals with an endolymphatic hydrops without further cochlear pathology. A normal or decreased SP and SP-AP ratio was regularly recorded in animals with both an endolymphatic hydrops and a variety of other histopathological changes in the inner ear. An increased second peak (N2) in the AP waveform was recorded from 63% (15/24) of the hydropic ears, equally divided over the four groups. There was no obvious correlation between the increased N2 and other electrophysiological or histological findings.
van Deelen
G W
GW
Department of Otorhinolaryngology, University Hospital, Utrecht, The Netherlands.
Ruding
P R
PR
Smoorenburg
G F
GF
Veldman
J E
JE
Huizing
E H
EH
D000200:Action Potentials; D000818:Animals; D001300:Audiometry, Evoked Response; D003051:Cochlea / Q000473:pathology* / Q000503:physiopathology; D007758:Ear, Inner / Q000473:pathology; D004487:Edema / Q000473:pathology* / Q000503:physiopathology; D004712:Endolymphatic Sac / Q000473:pathology / Q000503:physiopathology; D006168:Guinea Pigs