New generation of ‘bionic ears’ restore hearing to profoundly deaf people
By Nicola Davis
Sitting at the kitchen table rolling a ball of Play-Doh, Oliver Campbell is a picture of childhood contentment. At just under two years old he is experimenting with words and is happily peppering his creative endeavours with them. But inside Oliver’s head something extraordinary is happening. Currents from tiny electrodes, curled inside the snail-shaped cochlea of his inner ear, are stimulating his auditory nerve, allowing him to hear the thud of the Play-Doh and the creak of the chair and to assimilate the words of encouragement from his grandmother next to him.
Take them away and Oliver’s world would be thrown into confusion.
Diagnosed with auditory neuropathy spectrum disorder (ANSD) at barely 24 hours old, Oliver was born unable to make sense of the sounds around him. For his parents, Chris and Claire Campbell, it was devastating.
Lightning, they realised, had struck twice. Five years earlier Oliver’s sister, Alice, was also born with ANSD – although it took nearly 18 months for the diagnosis to be given. “It was a massive shock,” Claire says. “There’s no history of deafness at all in either side of the family.” Indeed the couple’s first child, Joseph, has no hearing difficulties at all. But when Alice didn’t seem to be learning to speak as her older brother had, the Campbells knew something was wrong.
The diagnosis was a bombshell. “Every hope and dream that you’ve ever had for this little child sitting in front you gets blown out of the water,” says Claire.
For Alice and her younger brother, something in their ears had gone badly awry. And it was going to take surgery, training and some seriously hi-tech kit before the clattering, chattering, bustling world would come alive.
Hearing is a sense most of us take for granted, but in reality it resembles a convoluted, anatomical version of the board game Mousetrap, played out within the fiendishly intricate architecture of the ear.
The ball is set rolling when sound waves arrive at the outer ear and are funnelled down the ear canal where they end up banging into the eardrum. The vibrations from the eardrum move a tiny connected bone called the hammer, which is hooked up to further biological ironmongery in the form of the anvil which is linked to the stirrup. The latter rests against part of the inner ear which leads on to the spiral-shaped cochlea.
And it is within the cochlea that things get technical. As the stirrup vibrates, it causes fluid within the inner ear to move back and forth – motion that is picked up by a membrane and passed on to tiny hair cells inside the cochlea. When the hair cells waggle, they release chemicals known as neurotransmitters that trigger electrical impulses in auditory nerve fibres close by. These signals whiz along the auditory nerve to the brain where they are deciphered. Perhaps surprisingly the hair cells, and hence auditory nerve fibres, are laid out like a piano keyboard – those in the outer part of the cochlea’s spiral respond to high frequency sound, while those near the tight curl at the centre react to low frequencies.
There is no doubt it’s a complex set-up, and one of evolution’s finest achievements. But when something goes wrong, the consequences can be devastating. For Oliver, Alice, and many other patients, the problem was located in the cochlea. While ANSD is a broad term encompassing a range of causes, and symptoms that can vary in severity daily, the upshot is that sound waves reach the hair cells, but are then scrambled into an incoherent signal or fail to be turned into electrical signals at all. But cochlear implants can make a world of difference. “For us it boiled down to a black and white decision,” Claire says. “It was, if you want your child to have hearing this is your only hope.”
Boasting an array of highly sophisticated technology, these implants have unsurprisingly been called “bionic ears”. Their staggering ability to create a sense of sound is down to a flexible electrode array that is gently nestled inside the cochlea during surgery. Finer than fishing twine, these wires allow the conventional auditory pathway to be sidestepped, changing the lives not only of those with ANSD, but also those with the missing or damaged hair cells or a damaged auditory nerve typical of “sensorineural” hearing loss.
Let’s reset the Mousetrap. Now sounds are picked up by an external microphone, hooked over the ear, and turned into a digital “score” of electronic stimulation patterns by a processor. This information is then transmitted wirelessly across the scalp, together with a dose of energy, where it is picked up by a coil under the skin and passed to the implant where the digital score is converted into electrical pulses. These are sent to the electrodes within the cochlea, where they artificially trigger electrical impulses in the auditory nerve fibres, bypassing the role of the hair cells. But while each hair cell stimulates only a few of these fibres, the electrical pulses of a cochlear implant trigger much larger areas. It’s a bit like playing a piano with giant hands – big bunches of keys get hit all at once. Yet, wonderfully, the mechanism works. It’s elegant, it’s sophisticated, and it changes lives.
“You can see it first thing in the morning when Ollie first puts his ears on,” Claire explains over the sound of her son happily playing. “The noise starts coming and he sort of brightens up and lightens up and you know his world is much more open.” The technology has also enabled Alice to attend a mainstream hearing school, learn to play the drums and enjoy listening to music – her favourite tunes being a combination of Queen and hits from Annie. It’s been a long journey for the Campbells, and one that has been intimately shared through their blog Alice’s Ears. But their hopes and dreams have returned. “Alice is flying now at school,” says Claire. “I am so proud of her and I’m so amazed by the technology and what it has given her.”
Yet it is technology that, nearly 40 years ago, barely seemed possible. “In the very beginning there was a lot of scepticism, mostly by neurophysiologists,” reveals Professor Ingeborg Hochmair when we meet in the swish surroundings of the Med-El innovation centre in Innsbruck, Austria. “They couldn’t believe it could work to stimulate just a few locations in the cochlea, and by stimulating around eight to 20 or so locations replace the function of 25,000 nerve fibres which there are in a normal auditory nerve, ” she says. “But it works.” As CEO of Med-El, one of the biggest cochlear implant companies worldwide, Hochmair is recognised as a pioneer of the technology – an accolade that last year saw her share the Lasker prize, an international award in the field of medical research.
The new innovation centre, a futuristic-looking construction opened just last year, is a testimony to the success of her vision and hard work. But the process of constructing a cochlear implant is also impressive. Peeking through into the clean rooms, I see a host of figures in gowns and masks busily peering down microscopes, carefully inspecting the laser welding of individual implants or checking a silicone seal is perfect. Few parts of the process are automated, and it is claimed that if a user tells the company the number of their implant, Med-El can pinpoint the people who built it. It’s a handmade device for a very personal application.
And it is a cause to which Ingeborg Hochmair has devoted her life. Having decided at just 13 years old that she wanted to pursue a career in biomedical technology she went on to study electrical engineering in Vienna. It was there that she and her future husband, Erwin Hochmair, became involved in the nascent field of cochlear implantation. Working with researchers, surgeons and, crucially, patients, they soon notched up an impressive list of successes, and in 1990 began employing staff at Med-El. “As inventors we wanted to see this become available for potential users,” she says. At the time both were employed in academia, which Ingeborg later left to head the growing company. She believes their mutual passion for the technology has contributed to her success. “This is a very lucky constellation,” she says of the partnership.
But while the technology has developed in leaps and bounds, Hochmair believes there is more to do. “There are still so many children that still have no access to the technology in various countries.” And financial outlay is not the only reason. “It’s awareness: many families just don’t know about that possibility. It’s infrastructure in some countries,” she says.
With children, it is a race against time. For those born unable to hear, it is crucial to implant the devices at a young age, preferably before two years old and ideally nearer nine months, to maximise the child’s ability to develop speech, language and listening skills. Without the input of auditory signals, the brain does not fully develop the ability to decipher sound, and as time ticks by this capacity for change – known as plasticity – decreases. What’s more it has been suggested that, if unused, these areas of the brain gradually become reassigned to tackling other tasks.
Even with a cochlear implant, there are further hurdles to face in harnessing the technology. “Somebody told me once that [having] a cochlear implant is a bit like being handed a key to a Porsche and not knowing how to drive,” says Anita Grover. “The brain has access to all this sound but it has to really learn to make sense of it.”
As chief executive of Auditory Verbal UK , a charity that provides therapy to youngsters getting to grips with their bionic ears, Grover is passionate about helping others to make the most of the technology. “I would like all children whose family wants them to be able to listen, speak and achieve to have access to auditory verbal therapy to help them maximise the potential of their cochlear implants,” she says. “There is a very small window where there is plasticity in a young brain, which means there is a real opportunity to maximise the development of listening and spoken language. If you get the early intervention right with the right technology and habilitation then you get the opportunity for deaf children to realise their potential. And that potential should be the same as a hearing child.”
Grover is well acquainted with the technology. Having experienced progressive hearing loss, by her late 20s hearing aids were no longer helping. As a civil servant she had relied heavily on lip-reading, but it was far from ideal. “I would be in a meeting [with] 15 to 20 people around the table and it was like Wimbledon,” she says. “It’s so incredibly tiring – you’ve got no backup.” In the end, a cochlear implant became necessary. “Without a cochlear implant I hear nothing at all, absolutely nothing,” she says. “It changed my life. I had gone through that process of my hearing deteriorating whereby I was becoming more and more withdrawn. I wouldn’t want to be in a social situation for fear of missing part of the conversation or something having been said, or perhaps getting the pitch wrong – shouting in a quiet place or being quiet in a noisy place.” And there are sounds you would never want to miss. “When the first of my twins was born he came out screaming,” says Grover. “I would not have heard that if I didn’t have a cochlear implant.”
But adults are in danger of being overlooked. Recent figures from the charity Action on Hearing Loss reveal that one sixth of the UK’s adult population have some form of hearing difficulties while a 2013 study suggests only 5% of adults whose life could be improved by cochlear implants actually receive one. “For adults, I would like to see improved access to at least one implant and ideally two,” says Grover.
It’s the dark side of the success story. Policy introduced in 2009 by the National Institute for Health and Care Excellence (Nice) dictates that while children deaf in both ears should receive two implants as a matter of routine, adults are allowed only one – unless they have a second disability, such as blindness, that makes them more reliant on hearing. It’s an issue that Labour MP Lilian Greenwood put squarely to the House of Commons in November. “A growing body of evidence indicates that bilateral implants provide added improvements in speech perception in noisy environments over unilateral implantation, and better sound localisation, leading to improved quality of life,” she said.
Azhar Shaida, consultant otologist and cochlear implant surgeon at the Royal National Throat, Nose and Ear hospital agrees but says: “The problem is down to money versus benefit.” With the assessment, implant, surgery and a year’s therapy costing £38,000-£45,000 for a single implant it’s an expensive business, although with discounts available on a second device and only one hospital procedure necessary if implanted simultaneously, the cost of bilateral implantation is not double the price. Even then Nice doesn’t believe the advantages boost quality of life enough, compared with the life-changing effect of the first implant, for adults to merit the cost.
Users such as Stuart McNaughton, a lecturer at Westminster Business School who also works for cochlear implant firm Advanced Bionics, say adults deserve better. “I pushed for two years [for] the NHS to give me the second one,” he tells me over coffee amid the bustle of Waterloo station. “Because I teach, part of my livelihood is very dependent on my ear working and, you know, sometimes things go wrong and if the one ear that you’ve got goes wrong you lose your livelihood.” Fundamentally, he says, it is about experiencing the world those of us who can hear take for granted. “It makes me the way I should have been, the way you are.”
But McNaughton is one of a small group of adults with bilateral cochlear implants. And like Greenwood, he believes it is high time attitudes towards adults changed. “I understand that children need more input because they are developing language and they are developing skills, but what about all the people over the age of 18, 19, 20, 21? They should be allowed bilateral implants as well. Society puts pressures on adults too – relationships, jobs – it’s a rat race out there.”
It’s a call to arms that resonates across the medical profession. As Shaida explains: “Two ears are better than one. Two cochlear implants are better than one.” The situation is particularly desperate for patients who have suffered from meningitis. “With meningitis you often get obliteration of the cochlea,” he says. “Normally for the meningitis patients we fast track them so that we can get the implant in as fast as possible before the cochlea becomes completely blocked and it’s impossible to do an operation.” For such patients simultaneous bilateral implantation could be crucial. “If we came back later on to implant the other side because the first side had failed, it [may not] be possible because of the blockage.”
But the 2009 Nice guidelines make it clear: even in such situations simultaneous bilateral implantation is simply not an option.
The introduction of the guidelines has also fuelled fears of deepening inequalities. “What we are seeing is a number of patients are opting to have one done on the NHS and having the second one done privately. Which is great – if you can afford it,” says Shaida.
David Selvadurai, consultant otolaryngologist surgeon at St George’s hospital, London, also believes it is time for change. “As a community of professionals we are keen to push this forward and we would like to see bilateral implants in adults become more acceptable,” he says.
But with the guidelines only reviewed every few years, he believes timing is everything. “What we don’t have at the moment is good cost benefit data to show that there’s enough benefit to the individual to demonstrate cost effectiveness for the NHS,” he says. “The danger that we have to be wary of is that the guidelines are reviewed before the necessary evidence is available.”
It’s a situation Shakeel Saeed, professor at UCL and the Royal National Throat, Nose and Ear hospital is determined to change. Working with colleagues at the Ear Institute, he is currently scoping a national, multi-centre prospective study on bilateral cochlear implantation in adults. “This is to create high quality evidence that Nice can then use to make a considered decision.” Gathering the evidence, he says, will take four to five years – and it won’t be cheap. But it’s a chance they can’t afford to miss.
[“Young Deaf Or Hearing Impaired Man Cupping One Ear To Listen” on Shutterstock]