title: Investigation of the physiological basis of summating potential changes in endolymphatic hydrops.
abstract: An increase in the ratio of the summating potential to the action potential components of the electrocochleogram is known to be a feature of endolymphatic hydrops. We investigated the value of the SP/AP ratio in response to condensation and rarefaction click stimuli delivered separately. In patients with electrophysiological evidence of endolymphatic hydrops there was found to be a significantly greater SP/AP ratio to condensation clicks than rarefaction clicks. This finding supports the hypothesis that the increased SP/AP ratio in hydrops is due to mechanical asymmetry of the basilar membrane.
authors.affiliation: Department of Otolaryngology, St Bartholomew's Hospital, London, England.
authors.forename: D J
authors.initials: DJ
authors.lastname: Gatland
authors.forename: R J
authors.initials: RJ
authors.lastname: Billings
authors.forename: R P
authors.initials: RP
authors.lastname: Youngs
authors.forename: N P
authors.initials: NP
authors.lastname: Johnson
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials; D001300:Audiometry, Evoked Response; D007758:Ear, Inner / Q000503:physiopathology*; D004487:Edema / Q000503:physiopathology*; D004712:Endolymphatic Sac / Q000503:physiopathology*; D006801:Humans