title: Impact of the insertion speed of cochlear implant electrodes on the insertion forces.
abstract: OBJECTIVE
  Objective of the present experimental research study was to examine the hypothesis that cochlear implant insertion speed can significantly affect the insertion forces.
  
  
  BACKGROUND
  Cochlear implant electrode insertion forces can influence the insertion trauma and the preservation of residual hearing. The effect of the electrode insertion speed on the insertion forces still remains unknown.
  
  
  METHODS
  Force measurements were performed while inserting human electrodes in an artificial scala tympani model at different speeds. For these measurements, an Instron 5542 Force Measurement System with a 10 N load cell and Nucleus 24 Contour Advance electrodes were used. Additionally, the insertion speed was measured through videos of 116 human implantations; these videos were recorded in our theaters and involved different surgeons and electrode types.
  
  
  RESULTS
  Progressive increase in insertion speed from 10 to 200 mm/min resulted in significant, proportional increase in the average insertion forces from 0.09 to 0.185 N and in the maximum forces from 0.18 to 0.42 N, respectively. The average insertion speed used in the theaters during human cochlear implantations was 96.5 mm/min (range, 42-165.2 mm/min) and depended on the electrode type and the surgeon.
  
  
  CONCLUSIONS
  High insertion speeds cause significant increase of the forces. Cochlear implant surgeons should use low and stable speeds during the insertion. Insertion speed close to the average value used in the theaters should be applied on experimental models, to approximate human implantation conditions.
authors.affiliation: Otothinolaryngology Department, Hanover Medical University, Hanover, Germany. Kontorinis.Georgios@mh-hannover.de
authors.forename: Georgios
authors.initials: G
authors.lastname: Kontorinis
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenarz
authors.forename: Timo
authors.initials: T
authors.lastname: Stöver
authors.forename: Gerrit
authors.initials: G
authors.lastname: Paasche
mesh_terms: D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D006801:Humans; D008953:Models, Anatomic; D012533:Scala Tympani / Q000601:surgery*