Cochlear implants can help deaf children achieve an astonishing quality of hearing and speech – but for best results the operation must be carried out before their first birthday.
First impressions with a cochlear implant
It rattles and clatters, cheeps and hisses… The simulation of the noises a cochlear implant (CI) can produce inside a person’s head is quite unpleasant for the uninitiated. Everything sounds strange and hard, tinny and artificial – like a train in the night or a hall full of pounding machines. And when someone speaks, the sound is enough to make Darth Vader eat his heart out.
But the brain, this miracle machine, can handle it. Step by step, it learns how to draw information from a cacophony of sound, how to filter speech out of it, how to distinguish single voices and assign them to individuals, even how to appreciate music. This takes a lot of practice and patience. But then, suddenly, out of the rattling and clattering, the cheeping and hissing, a whole world of hearing emerges.
Hearing – where there used to be nothing but silence. Without doubt, implants have changed the world for those people who are deaf or hard of hearing. Today speech can be understood very well and even music can be perceived so well with the implant that fine nuances of classical pieces can be appreciated. The devices are constantly being improved.
The first year is essential for the hearing development
But one fact is paramount: it is fundamentally important to implant deaf-born infants in both ears within their first year of life. “Only then can they develop hearing and speech to the same level as their peers who hear normally,” explains Professor Wolf-Dieter Baumgartner from the Department for Ear, Nose and Throat Diseases at the Medical University of Vienna, Austria, and the Karolinska University, Stockholm, Sweden.
The brain develops rapidly within the first months of life. The neurones – the nerve cells that carry messages to the brain – are hungry for input. Each impulse from outside, everything that’s seen, heard, felt and tasted, encourages new connections to develop between the nerves. The first two years of life are when the brain is designed to develop certain processes such as hearing. After that time, its capacity to do so is compromised. The auditory nerve in the ear receives information from sensory hair cells in the inner ear. If these hair cells are damaged, the nerve cannot do its work. And without stimulation, the area of the brain that is designed for hearing doesn’t develop.
However, this isn’t the case if the auditory nerve is stimulated in time, even if this is by electrical impulses from a technical device. “I used to think that children who were born deaf could never develop the same speech ability as those with normal hearing,” says Professor Baumgartner. “But children who have been implanted in both ears by the age of six months manage to do exactly that.” The doctor is enthusiastic about the innovations that cochlear implant technology has come up with, especially over the past 20 years. Back in 2001, Professor Baumgartner was treated with scepticism when, at a conference in Los Angeles, he reported about the great progress early-implanted children made. “Today everybody does it this way,” he says.
The sooner, the better
The first year is currently seen as an initial important time limit. Until then, implanted infants learn to hear and speak very well – as long as they do not suffer from delayed development. But even children who were implanted within their second year of life can often attend a mainstream school later on.
“These children go through all phases of speech acquisition, just like those with normal hearing,” says award-winning pedagogic audiologist Ulrike Rülicke, who specialises in working with CI users. “The later they get the CI, the more their speech development is delayed and the therapy becomes more complex. This can endanger their chance of attending mainstream school,” she explains.
If the operation takes place even later, the results won’t be as good. “Only half of those implanted between two to four years will make it to a mainstream school,” says Professor Baumgartner. “After the age of four, it is too late – those children will never achieve a normal level of hearing and speech, no matter how much therapy they have.” However, older children can benefit from an implant if they were able to speak and hear before losing their hearing.
Practice makes perfect
Therapy is vital after the operation. How long this lasts depends on the child, but typically, we are talking several years. “First of all, the device’s speech processor has to be adjusted to suit the individual,” Rülicke points out. “It’s often underestimated just how important this is.” Getting it right takes time and requires patience and constant exchange between the child, parents, therapists and technicians until the ideal settings are optimised.
CI training is vital to help the user to learn to hear and speak properly. But rather than formal training, it’s more a case of specialised speech therapists, educators or pedagogic audiologists supporting the child in his or her natural speech and general development. At the same time, they educate parents – and later, if possible, also nursery and schoolteachers – on how to support the child with their speech and hearing development. Talking to the child is really important. Rülicke says: “Early-implanted children who nobody talks to at home progress at a similar pace to those who are implanted later.” Too much consideration and under-challenging doesn’t help. “I see more deaf children who are under-challenged than overburdened. But these children need speech-intense surroundings, appropriate accompaniment and specific support.”
Professor Baumgartner agrees that if children are supported in an ideal way, they can achieve better marks in school than children with normal hearing.
The first infants who received a CI early in life are slowly reaching adolescence now. In fact, many of them have already superbly mastered the first step on their job ladder: to attend a mainstream school. For these children, the world of hearing has opened doors.
Working together for success
How well cochlear implant surgery works in children depends on several factors:
- early diagnosis through testing for deafness immediately after birth and during the following months
- early implantation of both ears, ideally from about six months of age to one year at the latest
- intensive and sensitive cooperation of everybody involved before and after the operation: ear, nose and throat specialists, paediatricians, speech therapists, speech scientists, audiologists, technicians, psychologists...down to parents, child, nursery and schoolteachers
- continuous therapeutic support over many years, geared to the child’s individual potential
- intensive participation of the whole family in all the child’s developmental stages
- good cooperation with educators, nursery and schoolteachers
The surgery is carried out under general anaesthetic and takes between two-and-a-half and three hours for two implants.
According to Professor Wolf-Dieter Baumgartner from the Department for Ear, Nose and Throat Diseases at the Medical University of Vienna, this is regarded as the safest surgical intervention in the ear, nose and throat area and is tolerated very well by babies. A few weeks after surgery, when the wounds are healed, the device is activated. During the following months and years, fine adjustments are made regularly. MED-EL provides a 10-year guarantee for the devices, which last on average for 25 years.