Three-year-old Grayson Clamp was born without cochlear nerves in both ears—total deafness. A cochlear implant was unsuccessful. But thanks to breakthrough research at the UNC School of Medicine, Grayson now has an auditory brain stem implant that allows him to hear.
For many people born with hearing loss, the problem lies in the inner ear, or cochlea, a spiral-shaped organ deep in the temporal bone. When this is the case, a cochlear implant can mimic how a normal cochlea functions. UNC is home to one of the largest pediatric cochlear implant programs in the country, and gives the ability to hear to over 100 children each year.
But rather than missing the thousands of microscopic sensory cells in his cochlea, Grayson was missing the nerve that connects the cochlea to the brain. After working with the pediatric cochlear implant team at UNC for two years, Grayson was identified as a good candidate for a clinical trial of an auditory brain stem implant (ABI) at UNC Hospitals.
The ABI device is similar to a cochlear implant, but instead of placing an electrode inside the cochlea, the surgeon places it on the cochlear nucleus of the brain stem. The electrode implanted on Grayson’s brain stem has been used before in adults with neurofibromatosis type 2, a debilitating disease that causes tumors to grow on the cochlear nerve.
During the insertion of the ABI, auditory physiologists work with the neurosurgeon and neurotologist to make sure the electrode is in exactly the right place.
“It’s much like programming a cochlear implant, but there are more unknown parameters,” says Holly Teagle, an audiologist and coinvestigator in the study. “That programming is different for every child. This study will teach us a lot about how to program the electrode and what the auditory system is capable of.”
Surgery is the first step. After spending the first three years of his life deaf, Grayson now has to learn how to process auditory signals and communicate verbally instead of through signs and gestures. Teagle says therapy is a critical component. “We don’t know how long it will take for Grayson to transition from visual to auditory language,” she says.
Grayson will return to the UNC School of Medicine many times over the next few years, as they track his progress and range of hearing. Grayson and his parents will also talk to UNC speech therapists from their home in Charlotte using “teletherapy,” an encrypted system that Teagle says is like a “fancy Skype.” Therapists will direct Clamp’s parents on how to help him to learn to listen and talk, and how to help his hearing and speech move along a normal developmental pattern despite being two or three years delayed.
The FDA approved the use of the ABI device in children in August of 2012. Grayson is the first of ten children to be a part of the clinical trials.
“We’re in the process of securing funds, and we have five or six other good candidates that we’re talking to,” Teagle says. “They’re coming from all over the country.”
Grayson’s surgery was performed by Craig Buchman, a professor of otolaryngology/head and neck surgery, and Matthew Ewend, chair of the Department of Neurosurgery in the UNC School of Medicine. Craig Buchman is also the principal investigator in the study. Matt Ewend, Holly Teagle, John Grose, and Shuman He are coinvestigators. All are faculty members in the UNC School of Medicine.