title: Foreign body or hypersensitivity granuloma of the inner ear after cochlear implantation: one possible cause of a soft failure?
abstract: OBJECTIVE
  A tissue response in the form of foreign body or a hypersensitivity reaction to cochlear implantation is common and may be one possible cause of a soft failure of cochlear implantation.
  
  
  BACKGROUND
  After a successful cochlear implantation, delayed failure may occur. The causes of a "soft" failure, that is, one in which device malfunction cannot be proven, are unknown.
  
  
  METHODS
  The histopathology of the temporal bones of a patient who, in life, had experienced a soft failure after cochlear implantation was described. In addition, the temporal bones of 8 other subjects who, in life, had undergone cochlear implantation were studied for evidence of a foreign body or hypersensitivity reaction.
  
  
  RESULTS
  In the case report, a necrotizing granulomatous giant cell reaction surrounded the cochlear implant electrode track through the mastoid and the middle ear and into the cochlea in both ears. There was osteolysis of the cribrose area, otic capsule, and bone between the facial nerve and the cochlea and destruction of the organ of Corti and spiral ganglion. In the additional 8 cases studied, a similar, although less pronounced, foreign body or hypersensitivity reaction was seen in 6 (75%) of the cases.
  
  
  CONCLUSIONS
  A foreign body or hypersensitivity reaction in the form of giant cells and lymphocytic cell infiltration is common after cochlear implantation and may be one possible cause of soft failure.
authors.affiliation: Department of Otology and Laryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, USA. joseph_nadol@meei.harvard.edu
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Nadol
authors.forename: Donald K
authors.initials: DK
authors.lastname: Eddington
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Burgess
mesh_terms: D000368:Aged; D001307:Auditory Perception; D019929:Cochlear Implantation / Q000009:adverse effects* / Q000379:methods; D005547:Foreign Bodies / Q000473:pathology*; D006099:Granuloma / Q000209:etiology* / Q000473:pathology; D006319:Hearing Loss, Sensorineural / Q000235:genetics / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D013701:Temporal Bone / Q000000981:diagnostic imaging / Q000473:pathology; D013997:Time Factors; D014057:Tomography, X-Ray Computed