Bilateral Cochlear Implantation Offers Significant Benefits in Difficult Listening Situations

How does unilateral cochlear implantation (UCI) compare with bilateral cochlear implantation (BiCI)?

Bottom line
Bilaterally implanted patients benefit significantly in difficult everyday listening situations such as when speech and noise come from different directions. Furthermore, bilaterally implanted patients are able to localize sounds, which is impossible for unilaterally implanted patients.

Background: In the last decades, cochlear implantation (CI) has become a widely applied intervention in the treatment of patients with severe to profound bilateral sensorineural hearing loss. Although many patients with unilateral CI achieve high levels of spoken word recognition when speech is presented in quiet, even the most successful users still experience difficulty in the presence of competing sounds and are poor at identifying the source of sounds. Binaural hearing has proven to be superior to unilateral hearing in both normal-hearing listeners and in those with binaural hearing aids. Based on this knowledge, hearing-impaired patients usually receive two hearing aids. However, when hearing aids do not provide sufficient benefit, it is standard clinical practice in the Netherlands to provide only one CI for adults.

Study design: Multicenter randomized controlled trial.

Setting: University Medical Centers of Utrecht, Maastricht, Nijmegen, Leiden, and Groningen.

Synopsis: Thirty-eight postlingually deafened adults were included in this study and randomly allocated to either UCI or simultaneous BiCI. The primary outcome was speech intelligibility in noise, with speech and noise coming from straight ahead (Utrecht–Sentence Test with Adaptive Randomized Roving levels). Secondary outcomes were speech intelligibility in noise with spatially separated sources, speech intelligibility in silence (Dutch phoneme test), localization capabilities and self-reported benefits assessed with different quality of hearing and quality of life (QoL) questionnaires. The research describes the results after two years of follow-up.

The researchers found comparable results for the UCI and simultaneous BiCI group, when speech and noise were both presented from straight ahead. Patients in the BiCI group performed significantly better than patients in the UCI group, when speech and noise came from different directions. Furthermore, their localization capabilities were significantly better. These results were consistent with patients’ self-reported hearing capabilities, but not with the questionnaires regarding QoL. The authors found no significant differences on any of the subjective and objective reported outcomes between the one- and two-year follow-up.

Citation: van Zon A, Smulders YE, Stegeman I, et al. Stable benefits of bilateral over unilateral cochlear implantation after two years. Laryngoscope. 2017;127: 1161–1168.