title: Comprehensive analysis of cochlear implant failure: usefulness of clinical symptom-based algorithm combined with in situ integrity testing.
abstract: OBJECTIVE
  Accurate diagnosis of cochlear implant failures is important for management; however, appropriate strategies to assess possible device failures are not always clear. The purpose of this study is to understand correlation between causes of device failure and the presenting clinical symptoms as well as results of in situ integrity testing and to propose effective strategies for diagnosis of device failure.
  
  
  METHODS
  Retrospective case review.
  
  
  METHODS
  Cochlear implant center at a tertiary referral hospital.
  
  
  METHODS
  Twenty-seven cases with suspected device failure of Cochlear Nucleus systems (excluding CI512 failures) on the basis of deterioration in auditory perception from January 2000 to September 2012 in the Melbourne cochlear implant clinic.
  
  
  METHODS
  Clinical presentations and types of abnormalities on in situ integrity testing were compared with modes of device failure detected by returned device analysis.
  
  
  RESULTS
  Sudden deterioration in auditory perception was always observed in cases with "critical damage": either fracture of the integrated circuit or most or all of the electrode wires. Subacute or gradually progressive deterioration in auditory perception was significantly associated with a more limited number of broken electrode wires. Cochlear implant mediated auditory and nonauditory symptoms were significantly associated with an insulation problem. An algorithm based on the time course of deterioration in auditory perception and cochlear implant-mediated auditory and nonauditory symptoms was developed on the basis of these retrospective analyses, to help predict the mode of device failure. In situ integrity testing, which included close monitoring of device function in routine programming sessions as well as repeating the manufacturer's integrity test battery, was sensitive enough to detect malfunction in all suspected device failures, and each mode of device failure showed a characteristic abnormality on in situ integrity testing.
  
  
  CONCLUSIONS
  Our clinical manifestation-based algorithm combined with in situ integrity testing may be useful for accurate diagnosis and appropriate management of device failure. Close monitoring of device function in routine programming sessions as well as repeating the manufacturer's integrity test battery is important if the initial in situ integrity testing is inconclusive because objective evidence of failure in the implanted device is essential to recommend explantation/reimplantation.
authors.affiliation: *Department of Otolaryngology, Kobe City Medical Center General Hospital; †Institute of Biomedical Research and Innovation, Kobe, Hyogo, Japan; ‡The Royal Victorian Eye and Ear Hospital; ∥Department of Audiology and Speech Pathology, University of Melbourne; ¶The HEARing Co-operative Research Centre; and §The Department of Otolaryngology, University of Melbourne, Melbourne, Victoria.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamazaki
authors.forename: Stephen
authors.initials: S
authors.lastname: O'Leary
authors.forename: Michelle
authors.initials: M
authors.lastname: Moran
authors.forename: Robert
authors.initials: R
authors.lastname: Briggs
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D001307:Auditory Perception / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D003054:Cochlear Implants; D018450:Disease Progression; D004581:Electronics; D019544:Equipment Failure Analysis; D005260:Female; D006311:Hearing Disorders / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure; D012189:Retrospective Studies; D055815:Young Adult