title: Apical hair cell degeneration causes the increase in the amplitude of summating potential.
abstract: CONCLUSIONS
  This study indicates that the lesion of hair cells in the apical turn of the cochlea can cause the change in the summating potential (SP)/Compound potential (CAP) ratio.
  
  
  OBJECTIVE
  Electrocochleography is a valuable clinic test for diagnosis of cochlear pathologies and the ratio of SP to CAP has been used to identify Meniere's disease. However, it remains controversial whether the increase of the SP/CAP ratio represents exclusively the endolymphatic hydrops.
  
  
  METHODS
  This study measured the SP and CAP in mice that displayed outer hair cell (OHC) degeneration in the apical section of the cochlea as their age increased.
  
  
  RESULTS
  As compared with the mice aged 8-10 months, the 24-month old mice displayed a significant increase in the amplitude of SP at 12-16 kHz. This result suggests that the degeneration of OHCs in the apical turn leads to the increase of the + SP at the middle frequencies. In contrast, the aging mice did not have a significant change in the CAP amplitude at super-threshold levels.
authors.affiliation: a Department of Otolaryngology , Chinese PLA General Hospital , Beijing , PR China.
authors.forename: Dayong
authors.initials: D
authors.lastname: Wang
authors.affiliation: b Center for Hearing & Deafness, Department of Communicative Disorders and Science , State University of New York at Buffalo , Buffalo , NY , USA.|c Department of Otolaryngology , Zhuhai Hospital Affiliated with Jinan University , Guangdong , PR China.
authors.forename: Binbin
authors.initials: B
authors.lastname: Xiong
authors.affiliation: a Department of Otolaryngology , Chinese PLA General Hospital , Beijing , PR China.|b Center for Hearing & Deafness, Department of Communicative Disorders and Science , State University of New York at Buffalo , Buffalo , NY , USA.
authors.forename: Fen
authors.initials: F
authors.lastname: Xiong
authors.affiliation: b Center for Hearing & Deafness, Department of Communicative Disorders and Science , State University of New York at Buffalo , Buffalo , NY , USA.
authors.forename: Guang-Di
authors.initials: GD
authors.lastname: Chen
authors.affiliation: b Center for Hearing & Deafness, Department of Communicative Disorders and Science , State University of New York at Buffalo , Buffalo , NY , USA.
authors.forename: Bo Hua
authors.initials: BH
authors.lastname: Hu
authors.affiliation: b Center for Hearing & Deafness, Department of Communicative Disorders and Science , State University of New York at Buffalo , Buffalo , NY , USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
mesh_terms: D000818:Animals; D001300:Audiometry, Evoked Response; D004195:Disease Models, Animal; D018072:Hair Cells, Auditory, Outer / Q000473:pathology / Q000502:physiology*; D008575:Meniere Disease / Q000503:physiopathology*; D008808:Mice, Inbred CBA; D011304:Presbycusis / Q000503:physiopathology*
keywords: Compound action potentials; hair cell loss; low frequency hearing loss; summating potentials