title: The role of extended preoperative steroids in hearing preservation cochlear implantation.
abstract: BACKGROUND
  Steroids have been shown to reduce the hearing threshold shifts associated with cochlear implantation. Previous studies have examined only the administration of steroids just prior to surgery. The aim of this study is to examine the role of extended preoperative systemic steroids in hearing preservation cochlear implantation.
  
  
  METHODS
  An animal model of cochlear implantation was used. 24 Hartley strain guinea pigs with a mean weight of 768 g and normal hearing were randomised into a control group, a second group receiving a single dose of systemic dexamethasone one day prior to surgery, and a third group receiving a daily dose of systemic dexamethasone for 5 days prior to surgery. A specially designed cochlear implant electrode by Med-EL (Innsbruck) was inserted through a dorsolateral approach to an insertion depth of 5 mm and left in-situ. Auditory brain stem responses at 8 kHz, 16 kHz and 32 kHz were measured preoperatively, and 1 week, 1 month and 2 months postoperatively. Cochlear histopathology was examined at the conclusion of the study.
  
  
  RESULTS
  At 1-week post operative, both groups receiving dexamethasone prior to implantation had smaller threshold shifts across all frequencies and which was significant at 32 kHz (p < 0.05). There were no differences among the three groups in the area of electrode related fibrosis. Spiral ganglion neuron (SGN) density was significantly higher in the group receiving steroids for 5 days, but only in the basal cochlear turn.
  
  
  CONCLUSIONS
  This is study demonstrates the benefits of extended preoperative systemic steroids on hearing outcomes and SGN density in an animal model of cochlear implantation surgery.
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada; School of Surgery, University of Western Australia, Perth, Western Australia, Australia. Electronic address: jafri.kuth@gmail.com.
authors.forename: Jafri
authors.initials: J
authors.lastname: Kuthubutheen
authors.affiliation: School of Surgery, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Harvey
authors.initials: H
authors.lastname: Coates
authors.affiliation: Department of Anatomic Pathology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Corwyn
authors.initials: C
authors.lastname: Rowsell
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Julian
authors.initials: J
authors.lastname: Nedzelski
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Chen
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Lin
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001305:Auditory Fatigue / Q000187:drug effects; D003051:Cochlea / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D019929:Cochlear Implantation / Q000009:adverse effects* / Q000295:instrumentation; D003054:Cochlear Implants / Q000009:adverse effects*; D003907:Dexamethasone / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D005355:Fibrosis; D005938:Glucocorticoids / Q000008:administration & dosage*; D006168:Guinea Pigs; D006309:Hearing / Q000187:drug effects*; D034381:Hearing Loss / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D013136:Spiral Ganglion / Q000187:drug effects / Q000473:pathology; D013997:Time Factors
chemical_list: D005938:Glucocorticoids; D003907:Dexamethasone
keywords: Cochlear implantation; Corticosteroids; Guinea pig; Hearing preservation