title: Cochlear implantation in the mouse via the round window: effects of array insertion.
abstract: Animal models are the only means of assessing the effects of cochlear implantation (CI) at a cellular and molecular level. The range of naturally occurring and genetically-modified mouse strains which mimic human deafness provide excellent opportunities for auditory research. To date, there are very few studies of CI in mice. The main aims of this study were to develop a reproducible and viable technique to enable long term CI in the mouse and to assess the response of the mouse cochlea to implantation as a means of evaluating the success of the procedure. Electrode array implantation via the round window was performed in C57Bl/6 mice aged 3 and 6 months. The contralateral cochlea acted as a control. Auditory brainstem responses (ABR) were recorded prior to and following CI. Analysis showed greater threshold shifts in the implanted ear compared to the control ear post-implantation, but substantial preservation of hearing. There were no cases in which implantation caused a profound hearing loss across all frequencies. Cone beam computerised tomography and light microscopy confirmed correct placement of the electrode array within the scala tympani. Cochleae were prepared for histological examination. Initial analysis revealed encapsulation of the implant in tissue with morphological characteristics suggestive of fibrosis. Our results show that mouse CI via the round window offers a model for exploring tissue responses to implantation.
authors.affiliation: UCL Ear Institute, 332 Grays Inn Road, London WC1X 2EE, UK. Electronic address: nina.mistry.11@ucl.ac.uk.
authors.forename: N
authors.initials: N
authors.lastname: Mistry
authors.affiliation: UCL Ear Institute, 332 Grays Inn Road, London WC1X 2EE, UK. Electronic address: l.nolan@ucl.ac.uk.
authors.forename: L S
authors.initials: LS
authors.lastname: Nolan
authors.affiliation: UCL Ear Institute, 332 Grays Inn Road, London WC1X 2EE, UK. Electronic address: shakeel.saeed@ucl.ac.uk.
authors.forename: S R
authors.initials: SR
authors.lastname: Saeed
authors.affiliation: UCL Ear Institute, 332 Grays Inn Road, London WC1X 2EE, UK. Electronic address: a.forge@ucl.ac.uk.
authors.forename: A
authors.initials: A
authors.lastname: Forge
authors.affiliation: UCL Ear Institute, 332 Grays Inn Road, London WC1X 2EE, UK. Electronic address: ruth.r.taylor@ucl.ac.uk.
authors.forename: R R
authors.initials: RR
authors.lastname: Taylor
mesh_terms: D000367:Age Factors; D000818:Animals; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D054893:Cone-Beam Computed Tomography; D004195:Disease Models, Animal; D004424:Ear Canal / Q000000981:diagnostic imaging / Q000601:surgery; D004567:Electrodes, Implanted; D016057:Evoked Potentials, Auditory, Brain Stem; D006311:Hearing Disorders / Q000601:surgery*; D008810:Mice, Inbred C57BL; D009334:Neck Muscles / Q000000981:diagnostic imaging / Q000601:surgery; D012405:Round Window, Ear / Q000000981:diagnostic imaging / Q000601:surgery*; D012533:Scala Tympani / Q000000981:diagnostic imaging / Q000601:surgery*