title: Electrode migration in cochlear implant patients: not an exception.
abstract: OBJECTIVE
  It was the aim of this study to investigate the occurrence of electrode migration of a cochlear implant in patients with and without complaints.
  
  
  METHODS
  We performed a retrospective case review in a tertiary referral center. The electrode position was evaluated in 35 cochlear implantees, 16 with a CII HiFocus1 (non-positioner) and 19 with a HiRes90K HiFocus1J, using multiplanar reconstructions of the postoperative CT scans. Of 5 patients, a second scan was obtained to evaluate complaints of performance drop, vertigo, tinnitus, headache or nonauditory stimulation. Displacements of the electrode contacts were calculated and displacements of >1 mm were considered a migration. The possible correlation with implant type, insertion depth or presence of complaints was analyzed.
  
  
  RESULTS
  Migrations were detected in 10 patients (29%). There was a significant effect of the implant type in favour of the HiFocus1, but no relation with the original insertion depth of the device. In the 5 patients scanned because of complaints, two migrations were detected.
  
  
  CONCLUSIONS
  In our patient population, electrode migration was not uncommon and turned out to occur in patients with and without complaints.
authors.affiliation: Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Kim S
authors.initials: KS
authors.lastname: van der Marel
authors.forename: Berit M
authors.initials: BM
authors.lastname: Verbist
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Briaire
authors.forename: Raoul M S
authors.initials: RM
authors.lastname: Joemai
authors.forename: Johan H M
authors.initials: JH
authors.lastname: Frijns
mesh_terms: D000328:Adult; D000368:Aged; D058070:Asymptomatic Diseases; D002648:Child; D002675:Child, Preschool; D019929:Cochlear Implantation / Q000009:adverse effects*; D003054:Cochlear Implants / Q000009:adverse effects*; D004567:Electrodes, Implanted / Q000009:adverse effects; D005500:Follow-Up Studies; D005548:Foreign-Body Migration / Q000209:etiology*; D006261:Headache / Q000209:etiology; D006319:Hearing Loss, Sensorineural / Q000601:surgery*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology*; D012189:Retrospective Studies; D014012:Tinnitus / Q000209:etiology; D014717:Vertigo / Q000209:etiology; D055815:Young Adult