A new Stanford/Packard Children's study examined the benefits of cochlear implants - sometimes called "bionic ears" - for deaf children with developmental delays. The implants feed sound from a microphone outside the head directly to the auditory nerve, but typically require intensive speech and language therapy to be helpful for the recipient. In the past, many doctors have opted not to use cochlear implants in developmentally delayed infants and toddlers - who are expected to later meet criteria for mental retardation - because they have doubted whether the implants would benefit these children.
The new study (subscription required) shows this approach may be wrong. The researchers, led by John Oghalai, MD, studied the few developmentally delayed deaf kids who do get cochlear implants. They found that these children get implants an average of 11 months later than typically developing children, meaning that they miss 11 months of potentially valuable sensory input at a time when brain development should be racing along. The late implantation took a toll, as our press release describes:
Not only did the delayed children start with lower intelligence, they also had slower intellectual development, perhaps because they spent more time unable to hear, the researchers reported. When the scientists statistically adjusted for the delay in implantation, the difference in rates of development disappeared, suggesting that lack of hearing plays a role in causing developmentally delayed children to fall further behind their peers.
“There is synergism between different sensory inputs,” Oghalai said. “And some of these kids are missing more than just hearing; they’re often having trouble with vision or touch as well. If you can fix one of the sensory problems, it might help to mitigate the effects of the other disabilities.”
Oghalai's team is now conducting more comprehensive studies to assess the value of cochlear implantation in a large cross-section of deaf children with developmental delays.
Previously: In people born deaf, auditory cortex takes on touch and vision, study finds
Photo by Chris & Shelley Mallinson
