A research study has been carried out at the University of York, England. The study compared the spatial listening skills and quality of life of children with unilateral or bilateral cochlear implants.
Spatial listening is the ability to attend to one source of sound in a mixture of sources in order to determine where it is located, in which direction it is moving, and what information it is conveying. These abilities are singular achievements of normal hearing. They allow listeners to know where to move to avoid hazards and where to look to see who is talking. They are crucial, therefore, for participation at home, for success at school, and for survival outdoors. Their breakdown is a major cause – possible the major cause – of auditory handicap in young and old age. (Source: University of York)
Children with unilateral or bilateral cochlear implants: Spatial listening skills and quality of life
There is worldwide interest in whether severely-profoundly deaf children should be provided with bilateral cochlear implants (two implants, one in each ear) rather than a unilateral cochlear implant (one implant in one ear). Potentially, implanting both ears rather than one could improve children’s spatial listening skills, meaning the ability to work out where sounds are coming from (by comparing the intensity and timing of sounds arriving at the two ears) and to understand speech in noise (by listening to the ear that gives the clearer speech sounds).
We assessed the spatial listening skills of 35 children with bilateral cochlear implants and 20 children with a unilateral cochlear implant. On average, children with bilateral implants performed better than children with a unilateral implant on tests of sound-source localisation and speech perception in noise. This study demonstrates, more rigorously than previous studies, that bilateral implantation for children is associated with improved spatial listening skills.
The group of children with bilateral implants included children who received both implants in a single surgery and children who received two implants in sequential surgeries. These two groups of bilaterally-implanted children showed similar listening skills, on average. However, the groups differed in age, so further work is needed to compare outcomes for simultaneous and sequential bilaterally-implanted children.
The study also obtained estimates of the quality of life of children with unilateral or bilateral implants. Measurements of quality of life contribute to the cost-effectiveness calculations that are used by policy-makers to decide which healthcare interventions to fund. Thus, the question of whether bilateral implantation improves quality of life has implications for healthcare policy. Judgements by children’s parents revealed no difference in quality of life between children with unilateral or bilateral implants. A follow-up study presented a group of adults (who were not the parents of deaf children) with written descriptions of a hypothetical deaf child with either unilateral or bilateral implants. The adults judged that the child with bilateral implants had higher quality of life than the child with a unilateral implant. The difference in quality of life between the two descriptions was large enough to mean that bilateral implantation would be considered a cost-effective use of resources within the NHS.
Evidence from these studies was taken into account by the National Institute for Health and Clinical Excellence in forming their guidance, which recommends that deaf children should have the option of receiving bilateral implants through the NHS. This work was reported in the Archives of Disease in Childhood and Ear and Hearing. These studies were supported by Deafness Research UK and Advanced Bionics.