title: Bilateral bone-anchored hearing aids (BAHAs): an audiometric evaluation.
abstract: OBJECTIVE
  Since the technique to implant bone-anchored hearing aids (BAHAs) with the use of osseointegrated implants was developed in 1977, more than 15,000 patients have been fitted with BAHAs worldwide. Although the majority have bilateral hearing loss, they are primarily fitted unilaterally. The main objective of this study was to reveal benefits and drawbacks of bilateral fitting of BAHAs in patients with symmetric or slight asymmetric bone-conduction thresholds. The possible effects were divided into three categories: hearing thresholds, directional hearing, and binaural hearing.
  
  
  METHODS
  Prospective study of 12 patients with bilateral BAHAs.
  
  
  METHODS
  Baseline audiometry, directional hearing, speech reception thresholds in quiet and in noise, and binaural masking level difference were tested when BAHAs were fitted unilaterally and bilaterally.
  
  
  RESULTS
  Eleven of the 12 patients used bilateral BAHAs on a daily basis. Tests performed in the study show a significant improvement in sound localization with bilateral BAHAs; the results with unilateral fitting were close to the chance level. Furthermore, with bilateral application, the improvement of the speech reception threshold in quiet was 5.4 dB. An improvement with bilateral fitting was also found for speech reception in noise.
  
  
  CONCLUSIONS
  Overall, the results with bilateral fitted BAHAs were better than with unilaterally fitted BAHA; the benefit is not only caused simply by bilateral stimulation but also, to some extent, by binaural hearing. Bilateral BAHAs should be considered for patients with bilateral hearing loss otherwise suitable for BAHAs.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Göteborg University, Gothenburg, Sweden. claudia.priwin@ks.se
authors.forename: Claudia
authors.initials: C
authors.lastname: Priwin
authors.forename: Stefan
authors.initials: S
authors.lastname: Stenfelt
authors.forename: Gösta
authors.initials: G
authors.lastname: Granström
authors.forename: Anders
authors.initials: A
authors.lastname: Tjellström
authors.forename: Bo
authors.initials: B
authors.lastname: Håkansson
mesh_terms: D000328:Adult; D000368:Aged; D001299:Audiometry; D001309:Auditory Threshold; D005260:Female; D006310:Hearing Aids; D006312:Hearing Loss, Bilateral / Q000534:rehabilitation*; D006314:Hearing Loss, Conductive / Q000534:rehabilitation*; D006319:Hearing Loss, Sensorineural / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D013069:Speech Reception Threshold Test