Wisconsin Public Television Waisman Center Day with the Experts  Cochlear Implants in Adults and Children Ruth Litovsky  June 23, 2012 UP732 CC >> We'd like to move onto a few research presentations. And what I'm going to do is begin by telling you a little bit about what we think of as some of the recent advances in cochlear implants, but also there are future possibilities. I always like to think of the work that we're doing in the community, and when I say community, I mean the field of cochlear implants which spans worldwide. I'd like to think of the work we're doing as representing the glass being both half full and half empty in the sense that we've made tremendous progress. We've learned so much about how to provide hearing to people who are either born deaf or acquire deafness later in life, and yet there are remaining challenges. You'll hear me talk both about, look, this is what we're finding, and this is really fantastic progress, and you'll hear me talk about, this is where these children or these adults aren't functioning as well as normal hearing people. And it's important to think about that bar. As Dr. Heatley described through the history of cochlear implants, initially the goal was to provide access to sound. I know there's sound there. Or access to some speech and language. 

The field, we always compared people to people who have hearing aids but who have severe to profound hearing loss. So the question was whether cochlear implants are doing a better job than hearing aids for that same population of people. Today we've changed the bar, we've raised the bar, we've changed the goals, and we talk about the desired outcomes as being equalizing, people who have cochlear implants with people who have normal acoustic hearing. We hope down the road this is what the devices will be able to do. We talk about possibilities for future development, this is what we're aiming for. So you've heard from Dr. Heatley about some of the history of cochlear implants, which is that we wanted to create devices that could provide access to sound. So that the user could communicate with verbal/oral communication, and not have to be necessarily, although some users are bilingual, in the sense that they use sign language as well. You've seen that the age of implantations that decreased. When I was first working in the field most of the children I met were receiving their implants no younger than age 3 or 4, and today we see many children receive them during infancy. And the criteria for implantation has changed in the sense that people used to be severe to profound, whereas today we see people who have quite a bit of residual hearing. 

Sometimes in the ear that gets implanted, but there's new devices out there that are hybrid in the sense that we provide a short array, so a partial cochlear implant in an ear that is also receiving acoustic hearing. Some people have very good residual hearing in the low frequency area, and to preserve hearing in that area, there's a new short array that is being tried on quite a few patients to preserve hearing in the lower frequencies, and to combine acoustic with electric hearing in that ear. That is a hybrid device, and we also have people who are bimodal. If you have serious, severe to profound hearing loss in one ear, but good residual hearing with useable acoustic hearing through a hearing aid in the opposite ear, you're a candidate for bimodal listening. You can be bilateral, but bimodal. There's a very small number of patients worldwide, and this is under serious debate, who have excellent hearing in one ear, but deafness the opposite ear. These are single-sided deafness people. Especially in Europe, they've implanted quite a few dozen people, and it's off the FDA label, but there's a handful of patients in the United States with single-sided deafness who would like to have hearing in the deaf ear. Often it's to relieve tinnitus. But there are a few people who don't have tinnitus who are interested in getting that device as well. 

I'm giving these examples to highlight this very important point which is that the criteria for implantation is changing, and it's continuing to change. I'm always surprised at what I see at the next conference I go to. A new candidate, a new population of people who seem to be benefiting from these devices. One thing that Dr. Heatley didn't really get into, but I think is important to mention, is that when people are not candidates for cochlear implants because we cannot stimulate the auditory nerve, there are devices that can be implanted more centrally in the brainstem. There are auditory brainstem devices, and there are now slightly higher devices that are going into the mid-brain. All of these are experimental, but there's a growing number of patients, always more in Europe than in the United States, little bit looser criteria surgeons who are a little bit more aggressive at trying out some of these procedures, but they end up coming back to the states at some stage, and we'll see a growing number of those as well. The other thing that is very interesting that we've seen, and I show a picture of this family here. This is a wonderful family who have traveled to Madison from far away from the west coast that participate in our research program a number of times. And the reason they're very interesting is that both of the parents who are congenitally deaf grew up speech reading and using sign language, and both of their children were born deaf. They decided that their children should have cochlear implants right away as soon as they were able to do that, and in fact both children were implanted bilaterally, and in fact each parent ended up getting a single cochlear implant as well. 

So six implants in that household, which is very interesting and wonderful management. They do beautifully. The children both speak and sign. What's interesting is that they're growing up in a household where the parents' speech isn't that well-articulated. They grew up deaf, and they do very well being mainstreamed, but their speech production is not what I would say, very clear. Yet the children's speech is outstanding. I think it's a testament to the speech therapy that these children are receiving and have received since the day that they could benefit from it. They're a wonderful family. Very supportive of the cochlear implant as a means of providing oral, verbal communication. I think this transition in the field of seeing more and more adults who is decided later in life to choose to get a cochlear implant is something that we didn't see 10, 15, 20 years ago either. 

So I'd like to tell you a little bit about what the field has shown, and then move into some of the research that we're doing here at the Waisman Center at the University of Wisconsin. In general in adults who receive cochlear implants, we see differences between people who have onset of deafness, either congenitally or early in life. This came up a little bit in the questions a few minutes ago. People who have onset of deafness during childhood, and people with onset of deafness during adulthood. It seems, moving up from the bottom of the slide, that the best outcomes in the sense that immediate recognition of voices at the turn-on of the devices are people whose onset of deafness is during adulthood. Sometimes people report that at turn-on they can understand their spouse's voice, or at turn on, they can understand speech and recognize music. Sometimes it takes a few months, but not that long. As we move up into the domain of people with onset of deafness congenitally or early in life, this is where it takes longer to see the benefits, and sometimes the benefits don't get as high as for people with onset of deafness during adulthood. This has almost everything to do with what happens to the auditory system when it's deprived of stimulation. This is why when we talk about children, we talk about early stimulation being very important. 

Adults who have spent many years, as we think of them being out of sound, have experienced degeneration in the neural circuits. What that means is that neurons lose the ability to send information to the brain. That is not something we can recover. We can recover the ability to use whatever information we have, but when the neurons can't stimulate anymore, or there are fewer of them, this is when getting information through the cochlear implant becomes more challenging. So through the fields, through hundreds of labs and research papers that have come out, this has been a consistent story between the age of onset of deafness and the amount of time being out of sound is important factor in outcomes. In children we see a similar story, but there's more opportunity for plasticity in children. We see with children born congenitally or early in life, early implantation leads to greater success, which is why the age of implantation has come down. Children with onset of deafness during early childhood also see excellent success. Sometimes they need more speech therapy. Sometimes it takes a little bit longer, but there are other factors that add to the variability that we don't understand yet. 

So today's standards, we implant early and/or soon after we see that they don't get much benefit from the hearing aid. I want to get into the nitty gritty of the research that we know from the field. One of the first questions is how do we test these kids. How do we know what they're hearing or what they're understanding. I wanted to show you a little video in which I can give you an example from our research domain, but it's not that different from what we do in the clinic in how we test language abilities in very young children. You're seeing a video of a young toddler. Actually, he was wearing body-worn devices. The little wires are hanging from behind his ears. He then got the ear level devices about a year later. This in particular experiment, which was done by Tina Grieco-Calub, who was a post-doctoral fellow here, we were interested in whether a child can look at pictures of words that the parents tell us they know. 

So the child knows the word baby, which is pictured here, or dog, doggy, which is pictured here. But the question is when they see these pictures in the real world can they hear the auditory information and match that auditory label to the visual object. So how good are they at in the real world or in the lab real world scenario can they do that task. How accurate are they, and how fast are they. So let me play this little movie for you. What I want you to do is watch the baby's eyes. In the data analysis we score 30 frames per second where the baby's eyes are moving. He's darting around the room. I'll play it twice. Before the sound comes on he's just looking around. 

After the sound comes on his eyes settle somewhere in the room. So watch his eyes. >> Look at the doggy. Where is it? >> Oh-oh, the sound didn't come on. Should we turn it up a little bit? >> Look at the doggy. Where is it? >> I'm going to turn it up again. Here we go. >> Look at the doggy. Where is it? >> Hopefully, what you saw, she said, look at the, but after she said the word doggy, his eyes settled on this part of the room which is where the picture of the dog is. Each kid does that many, many, many times. 

We alternate sides and pictures, and then we score the data for all the children. We also do this in the presence of noise. So they're listening to the woman, but there's a male voice in the background. Let me turn this down in case the too loud. [indistinguishable male voice] >> Female voice: Look at the doggy. Where is it? >> So the male's voice is actually ten decibels below that of the target female voice. For normal hearing people that is a no brainer. Plus ten decibel signal to noise ratio is very easy. But let's see what happens with these children. So what I'm showing you, the data, are the proportion of time that they're looking toward the correct target location as a function of time. 

Now over here at the top what you see are data from children who are normal hearing when they're listening and quiet. What happens is as soon as the word doggy comes on or baby, depending on the target, their eyes dart to the correct location. And they're almost one hundred percent correct. So they're fast and accurate. When we play the stimulus of noise, these normal hearing children drop. When we test children with cochlear implants, that's the filled triangles, they look like the normal hearing children who are listening with noise or maybe even a little bit worse. Remember, these are two and a half year old children. Children with cochlear implants have had less exposure to sound because they didn't get their cochlear implant until 12 or 18 months of age. They might be a year behind or have had a year less of auditory experience than the children who have normal hearing. So in a way they're doing pretty well. 

On the other hand, when they're listening and quiet, they look like the normal hearing kids listening in noise. To answer that question that someone asked about, what's it like to hear with an implant when you're first turned on. People report that it's a noisy system, and it takes time to get the clarity of the information from the cochlear implant. Maybe six months or a year isn't enough, and they need more time, which is why it sounds noisy to them early on. But they can do the task. I think the glass is half full part of the story is, my goodness, they can do the task. They sit there, they do it, they're learning the words. Yes. >> Just a clarification question, bilateral or unilateral? >> Good question, the question was are these children bilateral or unilateral. The answer is that in this study we tested many bilateral implanted and unilateral implanted children, and there was no difference on this particular task. 

But one thing, since you asked, is that the target speech and the noise both came from in front of the child. One thing we know about from having two cochlear implants, is that they specifically might be able to help us if we separate the target from the noise. That was not done in this experiment, but we're currently doing in our lab in that sound booth that you've seen down the hall. So hopefully we'll know the answer to that shortly. I had that on here. Children with one implant perform as well as children with two. Now as they get older, many children with cochlear implants catch up with their normal hearing peers in terms of their language abilities, but not all. Again this is the glass is half full, and half empty part of the story. These are data from a paper published a couple of years ago from a very, very large project that was managed by Dr. Niparko and his colleagues from Johns Hopkins. It's a very extensive paper. 

If you're interested, I highly suggest reading it. The basic part of the story is that the children who have normal hearing have a hearing have a mean trajectory of language outcomes that's up here. The mean trajectory of children with cochlear implants is down here. And this is what they were like before they got their device. You can see that they're closing the gap toward the kids with normal hearing, and that quite a few are following the trajectory of the kids with normal hears hearing. Yet there are a number of kids who are staying down here. This continues at other ages and other intervals of testing them. You can see that these are the children with normal hearing when they're older. Children with cochlear implants. Some are closing the gap, and some are staying down here. 

And so most of the children in that study were implanted unilaterally. I'd like to now move into bilateral cochlear implants, and start to get at some of the research that we're doing here in the lab, and ways that we think that bilateral implants may be able to help close some of that gap. As Dr. Heatley also mentioned, providing implants in two ears has now become a standard of care in many clinics around the world. Now the goal initially was to provide hearing and maybe replace the other ear. But into the '90s, and into the last decade or so, the goal was to try to bring them up to where normal hearing people are who have normal binaural acoustic hearing. What do we get from having access to sound in both ears when we have normal hearing? Well, the goal for the children with cochlear implants was to be able to mainstream them, to make hearing easier, but specifically binaural helps us hear noise, and to know where sounds are coming from. Many of the people who have bilateral implants report a significant change in the quality of life. It's easier to listen. I see my child is less tired. I have an easier time functioning in the real world, and you'll hear about this at the patient panel as well. 

We recently looked at 45 children who have bilateral cochlear implants, and we looked at language outcome measures, some of them very similar to the ones in the Niparko study. They were slightly older. What we looked at, and I'm just showing you a little bit of the data, was a non-language measure, a brief non-verbal IQ, and some core language measures. The first thing I want you to notice is that this bar is the mean, the average, of the normed population in the country of the children at that age. What you can see is that the kids who are coming to participate in our research are coming with parents who have very interested in supporting the research, and have the time and the ability to come here. These are very smart kids. Their brief non-verbal IQ is hovering not just around average, but very high, one or two standard deviations above the mean for the majority of them. In terms of language scores, when we first test them we see that many are within one standard deviation of the mean, and some are below the mean. Then as we follow them up, I'm regraphing the data, but what I want to show you is that the brief IQ as we follow them, the blue bar is the first time we tested them, which I just showed you in the last slide. A year later is the red bar, and another year later is the green bar. 

The brief IQ stays the same, hovers above average. Another measure that's not language related, a memory screen is also above average. What you see with the language is that they're getting better on average. As they're getting more experienced with their implants, their core language, their ability to listen or speak, is coming up at or above the mean. This is where the glass is more than half full because these kids are getting more experience, and catching up or surpassing their normal hearing peers, which achieves one of our goals which is to be able to mainstream these children with oral/verbal communication. Oh, my goodness, what happened to my slide? Oh, I see. Okay. Something happened to it. But I can still talk it through. So the other thing we're interested in is specifically binaural hearing which we know is important for the what question, can you understand what I'm telling you, and the where question, can you tell me where sounds are coming from. 

We do this because when we have sound arriving at both ears. Say we have sound coming from there, the sound reaches the ears at different times, and with differences in intensity or level. And the brain is doing a beautiful job of calculating those differences and being able to help us understand what in noise other where sounds are coming from. This is an example of something that's been studied over the years even with normal people, with something called the cocktail party effect. I'll sitting in the room full of people, they are all talking at the same time, I'm trying to focus on what one person is saying, and ignore what others are saying. How can I do this? Binaural hearing helps us do this, and the hallmark of binaural hearing is what we call is source segregation. What we're trying to do with people who have bilateral cochlear implants is improve their ability to do source segregation. So the way we do this in a research environment is that we position somebody in a room with loud speakers, and we're simulating a realistic listening environment. What we ask them to do is either tell us what they hear, so we might present sounds from different locations or where they hear these sounds. We do this with noise in the background or we do this in quiet. 

I want to show you a tiny bit of data from the work that we were doing. Here I'm showing you sound localization. So can you tell me where the sound is coming from. But they're listening either in quiet which is over here or in noise. Now this number here represents how bad they are. How many mistakes-- on average what's the error in degrees. If the sound is coming from over there, but you tell me it's over there, you made an error of 30-degrees. How good are you at solving this problem. What we're finding is that in quiet adults with bilateral implants rock. They are doing an incredible job of knowing where sounds are coming from in quiet. 

This is what they do with a single cochlear implant. This is the benefit then of having two cochlear implants. So these are the unilateral errors and bilateral errors. Now normal hearing people, as we add noise, and make the signal to noise ratio worse and worse, normal hearing people are holding out fairly well. Steady rise in error, but not too bad. What we see with people with bilateral implants is that their error rates rise dramatically in noise. Why is this important? All the studies on sound localization with bilateral implants, that sing the praises of bilateral implants, are done in quiet. And it's beautiful in quiet, right? One implant versus two is a significant improvement in sound localization. When we put people in noisy environments, this is where having bilateral implants isn't as good as we want it to be. Why not? What I'd like to do is take a minute to tell you what we're looking for in terms of future progress. 

What happens with two cochlear implants is that we put them on clinically, but we fit them as if we're fitting two ears independently. Is there anybody to blame? Not exactly. The manufacturers are working hard to miniaturize them, make the device better, faster. But what they haven't spent time doing is figuring out a way for the audiologists to map the devices bilaterally or force the devices to talk to each other. In a normal acoustic system, the ears are talking to each other right away, two synapses away from the cochlea, there's integration of inputs in the brainstem. Right ear, left ear, a couple of milliseconds, and the information is in the brain. With the bilateral implants that is not happening because we haven't done the engineering properly to do that. So are they doing better than with one implant? No question. We also have data for speech and noise showing that they're hearing in noise is significantly better with two than one. Have we closed the gap? I think there's still work to be done there. 

I have a couple of minutes for questions. I'll be here all day and I can take more questions throughout the day. Thank you very much for your attention. [applause]