title: Effect of embedded dexamethasone in cochlear implant array on insertion forces in an artificial model of scala tympani.
abstract: OBJECTIVE
  Loading otoprotective drug into cochlear implant might change its mechanical properties, thus compromising atraumatic insertion. This study evaluated the effect of incorporation of dexamethasone (DXM) in the silicone of cochlear implant arrays on insertion forces.
  
  
  BACKGROUND
  Local administration of DXM with embedded array can potentially reduce inflammation and fibrosis after cochlear implantation procedure to improve hearing preservation and reduce long-term impedances.
  
  
  METHODS
  Four models of arrays have been tested: 0.5-mm distal diameter array (n = 5) used as a control, drug-free 0.4-mm distal diameter array (n = 5), 0.4-mm distal diameter array with 1% eluded DXM silicone (n = 5), and 0.4-mm distal diameter array with 10% eluded DXM silicone (n = 5). Via a motorized insertion bench, each array has been inserted into an artificial scala tympani model. The forces were recorded by a 6-axis force sensor. Each array was tested seven times for a total number of 140 insertions.
  
  
  RESULTS
  During the first 10-mm insertion, no difference between the four models was observed. From 10- to 24-mm insertion, the 0.5-mm distal diameter array presented higher insertion forces than the drug-free 0.4-mm distal diameter arrays, with or without DXM. Friction forces for drug-free 0.4-mm distal diameter array and 0.4-mm distal diameter DXM eluded arrays were similar on all insertion lengths.
  
  
  CONCLUSIONS
  Incorporation of DXM in silicone for cochlear implant design does not change electrode array insertion forces. It does not raise the risk of trauma during array insertion, making it suitable for long-term in situ administration to the cochlea.
authors.affiliation: *INSERM, Minimally Invasive Robot-based Hearing Rehabilitation, UMR; †Otolaryngology Department, Unit of Otology, Auditory Implants and Skull Base Surgery, AP-HP, Hospital Pitie´ Salpêtrière; and ‡Sorbonne University, Université Pierre et Marie Curie, Paris, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Nguyen
authors.forename: Daniele
authors.initials: D
authors.lastname: Bernardeschi
authors.forename: Guillaume
authors.initials: G
authors.lastname: Kazmitcheff
authors.forename: Mathieu
authors.initials: M
authors.lastname: Miroir
authors.forename: Thomas
authors.initials: T
authors.lastname: Vauchel
authors.forename: Evelyne
authors.initials: E
authors.lastname: Ferrary
authors.forename: Olivier
authors.initials: O
authors.lastname: Sterkers
mesh_terms: D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D003051:Cochlea / Q000601:surgery*; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D003907:Dexamethasone / Q000627:therapeutic use*; D017276:Friction; D006801:Humans; D055595:Mechanical Phenomena; D008953:Models, Anatomic; D012533:Scala Tympani / Q000601:surgery*
chemical_list: D000893:Anti-Inflammatory Agents; D003907:Dexamethasone