title: Cochlear implantation for patients with single-sided deafness or asymmetrical hearing loss: a systematic review of the evidence.
abstract: OBJECTIVE
  A systematic review of the literature to evaluate the clinical outcome of cochlear implantation for patients with single-sided deafness (SSD) or asymmetrical hearing loss (AHL).
  
  
  METHODS
  We searched the PubMed, Embase, Cochrane Library, and CINAHL databases from their inception up to December 10, 2013 for SSD or AHL and cochlear implantation or their synonyms.
  
  
  METHODS
  In total, 781 articles were retrieved, of which 15 satisfied the eligibility criteria. Our outcomes of interest were speech perception in noise, sound localization, quality of life (QoL), and tinnitus.
  
  
  METHODS
  Critical appraisal showed that six studies reported on less than five patients or that they carried a low directness of evidence or a high risk of bias. Therefore, we extracted the data of nine studies (n = 112). Patient numbers, age, duration of deafness, classification of deafness, pure tone audiometry, follow-up duration, and outcome measurements were extracted from all nine articles.
  
  
  RESULTS
  Because of large heterogeneity between studies, we were not able to pool data in a meta-analysis. We therefore summarized the results of the studies specified per outcome.
  
  
  CONCLUSIONS
  There are no high-level-of-evidence studies concerning cochlear implantation in patients with SSD or AHL. Current literature suggests important benefits of cochlear implantation regarding sound localization, QoL, and tinnitus. Varying results were reported for speech perception in noise, possibly caused by the large clinical heterogeneity between studies. Larger and high-quality studies are certainly warranted.
authors.affiliation: *Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center Utrecht, Utrecht, The Netherlands; and †Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Alice
authors.initials: A
authors.lastname: van Zon
authors.forename: Jeroen P M
authors.initials: JP
authors.lastname: Peters
authors.forename: Inge
authors.initials: I
authors.lastname: Stegeman
authors.forename: Adriana L
authors.initials: AL
authors.lastname: Smit
authors.forename: Wilko
authors.initials: W
authors.lastname: Grolman
mesh_terms: D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D046088:Hearing Loss, Unilateral / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D011788:Quality of Life; D013017:Sound Localization / Q000502:physiology; D013067:Speech Perception / Q000502:physiology*; D014012:Tinnitus / Q000503:physiopathology; D016896:Treatment Outcome