title: Evaluation of a new mid-scala cochlear implant electrode using microcomputed tomography.
abstract: OBJECTIVE
  To investigate electrode position, depth of insertion, and electrode contact using an electrode array with a mid-scala design following round window (RW) and cochleostomy insertion.
  
  
  METHODS
  Eight fresh-frozen cadaveric bones were implanted; half via a RW approach and half through an anteroinferior cochleostomy using a styleted mid-scala electrode design.
  
  
  METHODS
  Microcomputed tomography was used to acquire oblique coronal and oblique axial reformations. Individual electrode positions along each array, insertional depth, and electrode contact were determined using National Institutes of Health Image J software.
  
  
  RESULTS
  All electrodes were inserted without significant resistance. The average angular depth of insertion was 436.5° for the RW group and 422.7° for the cochleostomy group. All electrodes acquired a perimodiolar position in the proximal segment and a lateral wall position at the basal turn, regardless of approach. Electrodes distal to the basal turn demonstrated a variable location, with 78% mid scala. One cochleostomy array fractured through the interscalar partition (ISP), acquiring a scala vestibuli position. The odds ratio for either abutting the modiolus, ISP, lateral wall or floor, or fracturing through the ISP were 2.7 times more likely following a cochleostomy insertion (P = .032).
  
  
  CONCLUSIONS
  The styleted mid-scala electrode design acquires a proximal perimodiolar position, a lateral wall location, as it traverses the basal turn, and most commonly a mid-scala position in the distal array. Interscalar excursion occurred in one of the cochleostomy insertions. Cochleostomy insertion is more likely to result in ultimate final electrode position adjacent to critical intracochlear structures.
  
  
  METHODS
  NA.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Frisch
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Carlson
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, U.S.A.
authors.forename: John I
authors.initials: JI
authors.lastname: Lane
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery.
authors.forename: Colin L W
authors.initials: CL
authors.lastname: Driscoll
mesh_terms: D002102:Cadaver; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D004567:Electrodes, Implanted; D004867:Equipment Design; D006801:Humans; D012405:Round Window, Ear / Q000601:surgery; D012533:Scala Tympani / Q000601:surgery*; D055114:X-Ray Microtomography / Q000379:methods*
keywords: Cochlear implant; deafness; microcomputed tomography; mid scala