title: Electrocochleography in children with auditory synaptopathy/neuropathy: diagnostic findings and characteristic parameters.
abstract: BACKGROUND
  The early diagnosis of AS/AN in children remains challenging because it exclusively relies on the detection of OAE and/or CM, while ABR are pathologically changed or missing. The aim of our study was to ensure the diagnosis of AS/AN, demarcate it to an outer hair cell damage and possibly differentiate between pre- and postsynaptic pathologies.
  
  
  METHODS
  We retrospectively evaluated the transtympanic ECochG results of ten children with AS/AN and compared them to a matched group with SNHL and without any signs of AS/AN. We analyzed the thresholds, latencies and - as a new parameter - the amplitude ratio between CAP and SP.
  
  
  RESULTS
  CM and SP thresholds were significantly lower than CAP thresholds in AS/AN patients and significantly lower than SP and CM thresholds in SNHL patients with comparable CAP thresholds. The CAP/SP ratio of amplitudes in SNHL children was more than three times (significantly) higher than in AS/AN children. The cutoff value was set at 1.0 in order to differentiate between both groups with a 80-90% sensitivity and specificity. It was not possible to differentiate between a pre- and postsynaptic type of AS/AN in our collective.
  
  
  CONCLUSIONS
  The ECochG can add valuable information for a precise differential diagnosis of AS/AN, especially in babyhood. We identified the CAP/SP ratio as a new parameter for differentiation between AS/AN and SNHL. When the CAP/SP ratio falls below 1.0, patients can be diagnosed AS/AN with high specificity and sensitivity. Significantly smaller SPL are needed to evoke SP and CM in the AS/AN group, thus showing the preserved hair cell function.
authors.affiliation: Department of Otorhinolaryngology, University of Cologne, Germany. Electronic address: konrad.stuermer@uk-koeln.de.
authors.forename: Konrad Johannes
authors.initials: KJ
authors.lastname: Stuermer
authors.affiliation: Department of Otorhinolaryngology, University of Cologne, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Beutner
authors.affiliation: Department of Otorhinolaryngology, University of Cologne, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Foerst
authors.affiliation: Institute of Medical Statistics, Informatics and Epidemiology (IMSIE), University of Cologne, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Hahn
authors.affiliation: Department of Otorhinolaryngology, University of Cologne, Germany.
authors.forename: Ruth
authors.initials: R
authors.lastname: Lang-Roth
authors.affiliation: Department of Otorhinolaryngology, University of Cologne, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Walger
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D001300:Audiometry, Evoked Response; D002648:Child; D002675:Child, Preschool; D003055:Cochlear Microphonic Potentials / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D006313:Hearing Loss, Central / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D016555:Matched-Pair Analysis; D012189:Retrospective Studies
keywords: Auditory neuropathy; Auditory synaptopathy; Cochlear microphonics; Compound action potential; Electrocochleography; Summating potential