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Researchers collaborate on $3.9 million NIH study of child-specific cochlear implant programming


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$3.9 million NIH grant funds engineering-VUMC study of child-specific cochlear implant programming
Dr. Rene Gifford works with patient Davy Hillis to program his cochlear implant at VUMC. (John Russell/Vanderbilt University)

Researchers from the School of Engineering and Vanderbilt University Medical Center are working to improve outcomes for children with significant hearing loss by providing individualized, prescription-like programming for their cochlear implants.

The study, funded by a $3.9 million grant from the National Institutes of Health, to aims to determine whether the approach will impact a child’s ability to acquire speech, language and literacy skills. Children now receive the same type of cochlear implant programming as adults even though a child’s ability to process speech information and discriminate pitch is much less developed, according to the researchers.

“We’ve taken what we know about programming cochlear implants for adults and applied that to children, and it has worked reasonably well,” said Rene Gifford, professor in the Department of Hearing and Speech Sciences and Director of the Cochlear Implant Program at the Vanderbilt Bill Wilkerson Center. “But the issue is that we aren’t using our underlying knowledge of what the child is actually doing with that signal to acquire language and develop literacy skills.”

Because the pitches that come through cochlear implants are not as finely resolved as the ones received through a normal-hearing ear, children are using an impoverished signal and a less-than-full pitch range as their sole auditory source to develop speech and language.

“Adults have a well-defined pitch map in their brain, so if you give them a little bit of information from different sources, they can fill in the rest. Children don’t have that,” said Stephen Camarata, professor of hearing and speech sciences. “So, our question is: Is it reasonable to apply these adult data to children who haven’t yet developed that system? And, more importantly, can we improve outcomes by individualizing input?”

Gifford and Camarata are the study’s principal investigators. The research team also includes Cornelius Vanderbilt Professor of Engineering Benoit Dawant, a professor of electrical engineering; Jack Noble, assistant professor of electrical engineering and computer engineering; and Dr. Robert Labadie, professor of otolaryngology / head and neck surgery.

To create a personalized programming approach, the research team will compare pre- and post-operative computed tomography scans to map out the patient’s electrode array and interface to determine whether the electrodes align at a uniform distance from the neurons in the cochlea. The further each electrode is from the nearest group of auditory neurons, the greater the electrical charge needs to be to achieve auditory perception.

As the charge increases, the spread of electrical excitation becomes broader, potentially causing interference of the signal rather than usable information.

“If you have an electrode that’s farther away from the neurons and you have to boost the signal level for detection, that signal will spread and make it more difficult for the listener to discriminate pitch,” said Camarata.

Once these gaps are identified, the team can selectively deactivate interfering electrodes in the cochlear implant, optimizing it for each patient based on individual anatomy and electrode placement. As a result, Gifford and Camarata hypothesize that children will be able to take better advantage of both pitch and timing information.

“This study has the potential to revolutionize audiology because right now, we’re treating cochlear implants like they’re a one-size-fits-all device,” said Gifford.

An internal seed grant from the Wilkerson Center allowed the team to test and obtain preliminary data on 36 children, of which the majority showed significant improvement in auditory perception and speech production. A few children showed no noticeable benefit, and none of the children performed worse because of the programming change.

“We know that children aren’t just ‘little adults,’ but it is not always easy to determine how to individualize our treatments to account for their unique characteristics,” said Anne Marie Tharpe, chair of the Department of Hearing and Speech Sciences.

“This team has made some big steps in personalizing the cochlear implant mapping process for these young patients with hearing loss who have the potential to result in significant improvements in developmental outcomes,” she said.

Enrollment for the study will begin in the late spring 2019.

For more information, contact Gifford at rene.gifford@vanderbilt.edu or Camarata at stephen.camarata@vumc.org.

Original story by Kelsey Herbers for VUMC Reporter