Whilst the benefit of a second cochlear implant in people with bilateral deafness is well established, the benefits of implantation for single sided deafness with normal contralateral hearing have been much more modest. The reasons for this are varied, in so far as they are known, but are thought to be due to the imbalance caused by having one ear with notably superior hearing. Implants, for all their advancements, cannot replicate normal hearing. Most of the studies in this area have considered adults, so this series of seven children being implanted for unilateral hearing loss is interesting. There was a notable improvement in sound localisation, but the benefits for speech perception, particularly in noise, were small, and the majority of measures did not reach statistical significance. A major drawback of the study is the time of onset of hearing loss. The authors assume that in most patients the deafness is congenital, but this is hardly supported by only one patient failing newborn screening. This is highly relevant as, particularly in a paediatric population, the length of deafness is crucial to determining outcome – and this is likely to be the case even in unilateral deafness, where restoring binaural hearing relies on neuroplastic central processes, and not just bilateral stimulation. Nevertheless, any data that adds to our understanding of this area is to be welcomed, and it helps us get a clearer picture of the best treatment of children in this situation.
Cochlear implants in single sided deafness
Reviewed by Robert Nash
Usefulness of cochlear implantation in children with single sided deafness.
CONTRIBUTOR
Robert Nash
BM BCh, MA(Oxon), MRCS, MA, DOHNS, FRCS (ORL-HNS), Great Ormond Street Hospital, London, UK.
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