title: Scalar position in cochlear implant surgery and outcome in residual hearing and the vestibular system.
abstract: OBJECTIVE
  To evaluate the effect of the intracochlear electrode position on the residual hearing and VNG- and cVEMP responses.
  
  
  METHODS
  Prospective pilot study.
  
  
  METHODS
  Thirteen adult patients who underwent unilateral cochlear implant surgery were examined with high-resolution rotational tomography after cochlear implantation. All subjects were also tested with VNG, and 12 of the subjects were tested with cVEMP and audiometry before and after surgery.
  
  
  RESULTS
  We found that although the electrode was originally planned to be positioned inside the scala tympani, only 8 of 13 had full insertion into the scala tympani. Loss of cVEMP response occurred to the same extent in the group with full scala tympani positioning and the group with scala vestibuli involvement. There was a non-significant difference in the loss of caloric response and residual hearing between the two groups. Interscalar dislocation of the electrode inside the cochlea was observed in two patients. A higher loss of residual hearing could be seen in the group with electrode dislocation between the scalae.
  
  
  CONCLUSIONS
  Our findings indicate that intracochlear electrode dislocation is a possible cause to loss of residual hearing during cochlear implantation but cannot be the sole cause of postoperative vestibular loss.
authors.affiliation: * Department of Otorhinolaryngology, Oslo University Hospital , Norway.
authors.forename: Karl Fredrik
authors.initials: KF
authors.lastname: Nordfalk
authors.forename: Kjell
authors.initials: K
authors.lastname: Rasmussen
authors.forename: Einar
authors.initials: E
authors.lastname: Hopp
authors.forename: Ralf
authors.initials: R
authors.lastname: Greisiger
authors.forename: Greg Eigner
authors.initials: GE
authors.lastname: Jablonski
mesh_terms: D000328:Adult; D001299:Audiometry; D019929:Cochlear Implantation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D003054:Cochlear Implants; D012048:Correction of Hearing Impairment / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006309:Hearing; D006311:Hearing Disorders / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009760:Nystagmus, Physiologic; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D011474:Prosthesis Design; D012533:Scala Tympani / Q000000981:diagnostic imaging / Q000503:physiopathology*; D054738:Scala Vestibuli / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D058585:Vestibular Evoked Myogenic Potentials; D014722:Vestibule, Labyrinth / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014741:Video Recording