Comparing the benefits of bilateral and unilateral cochlear implants in children
Deafness Research UK awarded a two-year project grant to Dr Margaret Tait at the Ear Foundation in Nottingham to carry out a study comparing the pre-verbal communication skills of bilaterally implanted children (two cochlear implants) with age-matched unilaterally implanted children (one cochlear implant).
[Project grant, 2007-2009]
Increasing numbers of children are receiving bilateral cochlear implants worldwide, but evidence of the benefit of bilateral implantation is limited and relates to speech perception in noise and sound localisation.
Until now, there has been no evidence of comparative benefit in the development of early communication skills, which predict later skills of speech perception and intelligibility. Health care systems, parents/carers and professionals urgently need quality evidence comparing unilateral and bilateral cochlear implantation to influence their decision-making.
Video analyses of children’s developing communication skills were used to assess 27 prelingually deaf children aged under 3 years with bilateral implants before implantation and six and twelve months after. These results were compared with 42 age-matched unilaterally implanted children.
Results from the project showed that there was a difference in communication skills between children before cochlear implantation and 12 months after; it was shown that by the 12 month interval, bilateral implantation contributed to this change. This indicates that the bilateral children were receiving something extra from their two implants. Advantages of bilateral implantation for olderchildren listening in noise are already well documented; however, the present study has shown advantages in very young preverbal children.
The results seem to show that becoming accustomed to making use of both ears from an early age will give the child a good start towards listening to speech in noisy environments. Moreover, taking into account the fact that measures of preverbal communication predict long-term speech perception outcomes, it is likely that bilaterally implanted children will outperform unilaterally implanted children in this area as well.
