title: Acoustic Hearing After Murine Cochlear Implantation: Effects of Trauma and Implant Type.
abstract: OBJECTIVE
  To model the contribution of implant material and insertion trauma on loss of acoustic hearing after cochlear implantation in an appropriate animal model.
  
  
  METHODS
  Sixty-five C57Bl/6J mice underwent unilateral implantation with implant grade materials: 2 implant grade silicones and a third uncoated platinum wire. A sham surgery group was included as a control. Serial auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAEs) were used to discern effects on hearing over 22 weeks. Histologic measurements of damage to the organ of Corti and spiral ganglion were correlated with degree of hearing loss and material type.
  
  
  RESULTS
  Organ of Corti damage correlated with rate of hearing loss soon after implantation (0-2 weeks) but not subsequently (2-22 weeks). Organ of Corti damage did not depend on implant type and was present even in sham surgery subjects when hearing was severely damaged. Spiral ganglia appeared unaffected. There was no evidence of an inflammatory or toxic effect of the materials beyond the site of implant insertion.
  
  
  CONCLUSIONS
  Hearing loss and cochlear damage appear to be related to insertion trauma, with minimal effect on delayed hearing loss caused by different materials. In the C57Bl/6J mouse model, the sensory epithelium appears to be the location of damage after cochlear implantation.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, USA Department of Pediatric Otolaryngology, Children's Hospital Colorado, Aurora, Colorado, USA.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Kopelovich
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Robinson
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, USA Eskisehir Military Hospital, Eskisehir, Turkey.
authors.forename: Hakan
authors.initials: H
authors.lastname: Soken
authors.affiliation: Cochlear Technology Center Europe Belgium, Mechelen, Belgium.
authors.forename: Kristien J
authors.initials: KJ
authors.lastname: Verhoeven
authors.affiliation: Cochlear Ltd, Research and Technology Laboratories, Centennial, Colorado, USA.
authors.forename: Jonathon R
authors.initials: JR
authors.lastname: Kirk
authors.affiliation: Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Shawn S
authors.initials: SS
authors.lastname: Goodman
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, USA Department of Neurosurgery, University of Iowa, Iowa City, Iowa, USA marlan-hansen@uiowa.edu.
authors.forename: Marlan R
authors.initials: MR
authors.lastname: Hansen
mesh_terms: D000818:Animals; D001309:Auditory Threshold; D019929:Cochlear Implantation / Q000009:adverse effects*; D003054:Cochlear Implants; D016057:Evoked Potentials, Auditory, Brain Stem; D005355:Fibrosis; D046088:Hearing Loss, Unilateral / Q000209:etiology*; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D009925:Organ of Corti / Q000293:injuries / Q000473:pathology*; D017084:Otoacoustic Emissions, Spontaneous; D011474:Prosthesis Design; D013136:Spiral Ganglion / Q000473:pathology*; D013997:Time Factors
keywords: cochlear implantation; hearing loss high frequency; mice inbred C57BL; silastic