title: Electrode migration after cochlear implant surgery: more common than expected?
abstract: The overall complication rate of cochlear implant surgery is low and so-called electrode failures (electrode migration, misplacement, etc.,) account for only a minority of all complications. The aim of this study was to explore the prevalence of electrode migration as the cause for increased impedance values and non-auditory stimulation in the basal channels. Within the scope of a quality control process, the cochlear implant database of the Kuopio University Hospital (Finland) was reviewed. Patients with gradual elevation of impedance values and/or non-auditory stimulation of the basal electrode channels were re-examined and cone-beam computed tomography was administered. There were 162 cochlear implant recipients and 201 implanted devices registered in the database. A total of 18 patients (18 devices) were identified having significantly increased impedance values or non-auditory stimulation of the basal electrodes. Cone-beam computed tomography revealed extra-cochlear electrodes in 12 of these patients due to the migration of the electrode array. All extruded electrodes were lateral wall electrodes, i.e., straight electrode arrays (Cochlear CI422 and Med-El devices). The most common feature of electrode migration was the gradual increase of the impedance values in the basal electrodes, even though telemetry could also be unsuspicious. Electrode migration after cochlear implant surgery may be more common than previously reported. At surgery, special attention should be paid to the reliable fixation of the electrode array. This study underlines the importance of postoperative imaging after cochlear implant surgery.
authors.affiliation: Department of Otorhinolaryngology, Kuopio University Hospital, PO Box 100, 70029, Kuopio, Finland. aarno.dietz@kuh.fi.
authors.forename: Aarno
authors.identifier: http://orcid.org/0000-0001-6076-1037
authors.initials: A
authors.lastname: Dietz
authors.affiliation: Department of Otorhinolaryngology, Kuopio University Hospital, PO Box 100, 70029, Kuopio, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Wennström
authors.affiliation: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Lehtimäki
authors.affiliation: Department of Otorhinolaryngology, Kuopio University Hospital, PO Box 100, 70029, Kuopio, Finland.|Department of Otorhinolaryngology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Löppönen
authors.affiliation: Department of Otorhinolaryngology, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Hannu
authors.initials: H
authors.lastname: Valtonen
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D003051:Cochlea / Q000601:surgery; D019929:Cochlear Implantation; D003054:Cochlear Implants / Q000009:adverse effects* / Q000706:statistics & numerical data; D054893:Cone-Beam Computed Tomography; D017097:Electric Impedance; D004567:Electrodes, Implanted / Q000009:adverse effects* / Q000706:statistics & numerical data; D004569:Electroencephalography; D005260:Female; D005387:Finland; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011475:Prosthesis Failure
keywords: Cochlear implants; Cone-beam computed tomography; Electrode migration; Impedances