Cochlear implants were first approved for hearing restoration in the 1980s, but researchers are still studying the detailed nerve interactions that underpin their function. Shuman He, MD, PhD, professor and vice chair of research in the Department of Otolaryngology – Head and Neck Surgery at The Ohio State University Wexner Medical Center, has made big strides in advancing that understanding.
“I work with adult and pediatric patients who get a cochlear implant due to hearing loss,” says Dr. He. “The overall goal is to identify biomarkers based on the neural response generated by their system to predict cochlear implant benefit and to generate clinical tools based on scientific evidence to facilitate the programming process.”
The approach is to record the patient’s neural response in their auditory system and use that data to predict how well the patient will perform with their cochlear implant. Dr. He says they can “measure the response from the patient’s nerve, which is the first neural structure that receives the stimulation from a cochlear implant.”
In the last two years, Dr. He’s team developed new tools to quantify how well neurons are firing together in human cochlear implant patients. This process evaluates the nerve’s response to the sounds delivered by the implant, identifying whether the implant is the bottleneck or if another underlying issue is impacting hearing. A fundamental question is whether this is a cognitive issue, a device issue or a system issue.
Dr. He says, “How well the nerves fire at the same time determines how well the patient can understand the speech when there is background noise, which is the most difficult task for cochlear implant users.”
Many cochlear implant users can understand speech just fine in a quiet environment. But, Dr. He says, “Once you add some noise, it becomes mission impossible.”
The study, “Peripheral Neural Synchrony in Post-Lingually Deafened Adult Cochlear Implant Users,” was published in medRxiv.
Dr. He notes that although cochlear implants have been standard clinical medical treatment for 40 years for people with hearing loss, how the devices are programmed isn’t evidence-based. Different manufacturers produce devices, and each manufacturer will suggest a set of parameters to program the device. But those can range, Dr. He says, from 900 hertz (Hz) up to 5,400 Hz. “That’s a huge difference. If you ask the different manufacturers why they recommend those numbers, they can’t tell you.”
Due to her research and the resulting better understanding of the cochlear nerve, “we’ll be able to better recommend the programming process for each individual patient,” Dr. He says.
The research also reinforces the idea that pediatric patients are not just small adults. “We learn from adult patients, and it helps us to understand pediatric patients, but you should not treat children as little adults because they’re not. The etiologies between children and adults are so different. I feel that our service to patients can be improved if we have solid evidence and a better understanding of what we’re doing.”