How effective is bilateral cochlear implantation versus unilateral implantation in children with sensorineural hearing loss?
Background: The number of studies suggesting the positive effect of bilateral cochlear implantation in children with severe to profound sensorineural hearing loss has rapidly increased. However, second implants are expensive, and two systematic reviews have found no randomized controlled trials performed in children and a level of evidence too low to draw robust conclusions.
Study design: A review of 21 studies comparing a bilateral cochlear implant group with a unilateral implant group from Pubmed, Embase, and Web of Science, from inception up to July 25, 2013.
Setting: University of Amsterdam and VU University Amsterdam, Amsterdam, Netherlands.
Synopsis: Overall results show that there is weak or insufficient evidence in favor of bilateral implantation, and there is insufficient evidence to make a valid comparison between bilateral implantation and bimodal fitting (cochlear implant and hearing aid). There was a large benefit of bilateral implantation on spoken language comprehension and expression, but no differences between oral language scores.
There is consistent evidence of the benefit of bilateral implantation for sound localization. One year after second implant activation, there were no differences in speech perception in quiet, or in noise presented from either the front or the side between the bilateral and unilateral groups, although there was a major benefit for bilateral implantation when noise was presented on the side of the first or only cochlear implant. Bilaterally implanted children showed fewer distortions in their articulation. Although the bilaterally implanted children used their second device less often than their first, comparisons between the unilateral and bilateral groups did not reveal a difference after 12 and 24 months of cochlear implant use.
There were some limitations to this study, including clinical heterogeneity between studies that prevented data pooling, some data that could be extracted only from figures or graphs, and partially identical study populations in some study groups.
Bottom line: The second cochlear implant might be especially useful in sound localization and possibly also in language development, but there is currently no strong evidence to support the additional benefit of the second cochlear implant in children.
Citation: Lammers MJW, van der Heijden GJMG, Pourier VEC, Grolman W. Bilateral cochlear implantation in children: a systematic review and best-evidence synthesis. Laryngoscope. 2014;124:1694-1699.