Congenital deafness inhibits a child’s ability to learn speech and language. The most common treatment for deafness is the surgical placement of a cochlear implant, an electronic device that receives incoming sounds and electrically stimulates the auditory nerve, thereby bypassing the malfunctioning inner ear. Achieving optimal results with a cochlear implant requires programming it so that it appropriately stimulates the auditory nerve. To date, this process completely depends upon the measurement of subjective behavioral responses to define the threshold of hearing. However, congenitally-deaf children have no concept of what sound is, and thus have highly variable behavioral responses. These issues are even more complex in children with cognitive delays, a condition that often co-exists with congenital deafness, because they often have no behavioral responses.
We propose to use near-infrared spectroscopy (NIRS) in deaf children who hear with a cochlear implant to optically image activity within the auditory cortex in response to speech stimuli. Our overall goal is to develop an objective measure of auditory perception that could be used to guide cochlear implant programming, even if behavioral responses are absent. We hypothesize that NIRS can provide an accurate and immediate measure of speech perception in deaf children hearing through a cochlear implant.
We have three specific aims:
First, we will correlate behavioral responses with NIRS responses from children who have used a cochlear implant for >2 years. This aim will test the hypothesis that NIRS thresholds accurately predict behavioral thresholds using patients with reliable behavioral thresholds.
Second, we will compare behavioral responses with NIRS responses from children at initial cochlear implant activation. This aim will test the hypothesis that NIRS thresholds immediately predict behavioral thresholds.
Third, we will determine whether cortical responses can be measured using NIRS from implanted children with cognitive delays. Because of their lack of behavioral responses, this patient population has a significant need for such technology and could benefit immediately from its use. This proposal is innovative because this technology has never before been applied to hearing-impaired patients. This research is translational and could have an immediate, significant positive impact on patient health because NIRS may prove to be a valuable clinical tool. It has the potential to guide cochlear implant programming in any patient with unreliable behavioral responses.