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New Way To Hear For Grayson: Brain Stem Implant

New Way To Hear For Grayson: Brain Stem Implant

CREATED Mar 31, 2014

CHAPEL HILL, N.C. (Ivanhoe Newswire) – Imagine being born profoundly deaf: missing the vital nerve needed for you to hear. Without it, you had no options; until now.

Born without the nerve that carries sound to the brain, 3-year-old Grayson Clamp became one of the first children in the U.S. to receive an auditory brain stem implant (ABI) at the University of North Carolina at Chapel Hill.

"The day that they turned it on was amazing," Nicole Clamp, Grayson's mom told Ivanhoe.

Since then, his mom says Grayson has blossomed, going from being unable to hear, to distinguishing sounds, to even developing some speech.

"He just seems calmer. He's just more comfortable in his environment in general," she explained.

The ABI works by stimulating the brain stem directly: turning sound received by a processor into electrical impulses delivered to the brain.

"Where before he wouldn't hear a jet on the tarmac, now he can hear the softest of whispers," Craig Buchman, MD, FACS, Director of the UNC Ear and Hearing Center at the University of North Carolina at Chapel Hill, told Ivanhoe.

Since Grayson's the first implant, it's hard to predict how his hearing will develop, but Dr. Buchman is optimistic.

"I'm hopeful, I'm super hopeful. And it seems like we are going in the right direction," he said.

Since Grayson was missing his auditory nerve, attempts at using a cochlear implant didn't work, which is why he enrolled in this trial.

His mom said he's been making such great strides that this August he'll enroll in a kindergarten readiness school for 4-year-olds so he can be around kids his age with no hearing difficulties.

RESEARCH SUMMARY

BACKGROUND:  More than 12,000 babies are born with hearing loss each year in the United States. Current technology now allows the accurate assessments of hearing in children starting within a few hours of birth. In fact, all states have mandates that testing of hearing be done in the newborn prior to discharge from the hospital. Children with undetected hearing loss may not be able to develop normal speech and language or acquire the cognitive abilities, like thinking, knowing, and judging, needed for learning. The early detection of hearing loss allows treatment and rehabilitation of the hearing-impaired child at a very young age.  (Source:http://www.medicinenet.com/detecting_hearing_loss_in_children/article.htm)

RISK FACTORS:  About 50 percent of hearing loss cases are genetic. However, there are a number of risk factors for hearing loss in children, so there are  numerous reasons why a child's hearing may need to be screened or tested. Common indications for a hearing evaluation include:

  • Speech delay
  • Poor school performance
  • Infectious diseases that cause hearing loss (like Down syndrome)
  • Frequent or recurrent ear infections
  • Medical treatments that may have hearing loss as a side effect, like some chemotherapy agents
  • Diagnosis of a learning disability or other disorder, like autism

(Source: http://www.medicinenet.com/detecting_hearing_loss_in_children/article.htm)

NEW TECHNOLOGY:  Cochlear implants (CI) are highly successful at restoring functional hearing, but Grayson was born without the nerve that carries sound to the brain. The auditory brainstem implant is similar in design and function to a CI, but the electrode is placed on the first auditory relay station in the brainstem, called the cochlear nucleus. The ABI stimulates neurons directly at the brainstem, bypassing the inner ear and hearing nerve entirely. Doctors start by setting frequencies in the implant for up to 20 electrodes. In the United States ABI's were previously only approved for adults with certain conditions. But now the FDA is testing it on children. (Source: http://www.asha.org/Publications/leader/2011/110315/Auditory-Brainstem-Implants.htm and http://www.mayoclinic.org/tests-procedures/auditory-brainstem-implant/basics/definition/prc-20022457

INTERVIEW

Craig Buchman, M.D., Professor of Otolaryngology and Head and Neck Surgery at the UNC School of Medicine and Director of the UNC Ear and Hearing Center, talks about the auditory brainstem implant for children.

So what kind of shape was Grayson in when you first saw him?

Dr. Buchman: Grayson failed his newborn hearing screen, like 1 in 1000 kids born in our state every year, so he underwent the normal evaluation which in our center requires that you undergo an MRI. On the MRI, it was noted that his anatomy was abnormal. He had a present cochlea, which is the sensing structure for hearing, but he didn't have the nerve. It might be better to say the nerve appeared either very, very small or absent; below the level that you could resolve it on the scan. So, because of that, we told the family that his chances to do great with a cochlear implant were pretty limited, but we still talked to them about it and actually placed a cochlear implant in Grayson first to see if it would make a difference. He used that for quite a while and didn't gain the kind of benefit that all of us were hoping for. And so that's why they chose to move forward with the trial.   

It's a pretty exciting trial and now it's been three kids that you implanted?

Dr. Buchman: Right.  

Can you talk about how it works?  

Dr. Buchman:  It's a device that picks up sound and it converts it to an electrical signal. Then the device is placed under the skin behind the ear and then wires take it inside .We placed it, during surgery, to a little spot on the brainstem and because there is no connection for normal sound to travel through the ear canal and the normal route, this basically bypasses all that and carries the signal right to the brainstem.   

So do the kids hear the same way that we would hear then?

Dr. Buchman: No. Normal hearing would use your ear canal and your eardrum and your hearing bones and then your cochlea converts that information to nerve signals that go to the brain. That whole systems is really function-less in Grayson. So, this bypasses all of that, and electrically stimulates right on the brainstem where the normal nerve would normally insert. 

How does he hear differently?  

Dr. Buchman: I would be guessing if I told you that we knew exactly what it is that he hears. But we know that when we stimulate that area with sound, that he responds to it and he, in fact, responds appropriately to some sounds. So beyond that, we're going to learn over time as Grayson grows up and becomes more articulate and tells us more as to what he is hearing. I think that's when we are going to learn what that really means.

What should we expect from him as time goes on, as far as his language development and everything else?  

Dr. Buchman: We're just going to have to see. We're very hopeful that he'll start to become more and more appropriate in terms of understanding, speech, and language and hopefully he'll start to develop speech. He has some really basic stuff now, but honestly I can't tell you that, cause it's hard to predict. When you're talking about the first child in a clinical trial, in our institution and not a lot of other children in the U.S. to look at, it's hard to make any predictions. There have been some children done in Italy, and elsewhere in the world, but we're still talking about relatively small numbers.

What has been his progression so far, the difference that you've seen?

Dr. Buchman: Well he's certainly sound aware. There is no question about that.  I mean he responds to many sounds. He can actually tell the difference between, for instance, different nursery rhymes. That's pretty powerful stuff. If he falls asleep with the device on and the dog barks or something happens, that may wake him up. So he's responding to sound in a real way. He has a few words now too. I think all is going in the right direction. I don't know that it's as fast as we see from a cochlear implant child. Cochlear implant children are on a little steeper trajectory, so it might be a little slower.

So this is really like a new frontier?  

Dr. Buchman:  It is a new frontier. I mean the device has been around for a long time. We're certainly not the first ones in the world to do this. It's not the first time this is being done, but in the United States in children, this is just starting to get going.  

How big of breakthrough would you say this is though for kids? 

Dr. Buchman: To put it in perspective, 1 in 1000 kids are born severe profoundly hearing impaired and a small, small, small proportion of those children would have this particular problem. So, if you're talking about from a public health perspective, how big of a breakthrough? I would say it's really small. I would say for a small niche of children that have no other options other than only to use sign language, this is another option and certainly might be something that would be useful for them to communicate better.

FOR MORE INFORMATION, PLEASE CONTACT:

Craig A. Buchman, MD, FACS
Department of Otolaryngology-Head & Neck Surgery
University of North Carolina at Chapel Hill
Tel: 919-843-4820
buchman@med.unc.edu