Cochlear implants provide hearing to sensorineural hearing loss patients through electrical stimulation of the auditory nerve. However, the current status of the cochlear implant leaves room for improvement in both engineering and biological aspects that could enhance the perception of sound. The condition of the auditory nerve in sensorineural hearing loss plays a major role in the processing of electrical stimulation, and promoting survival of the nerve has been shown to improve implant function. The current proposal aims to not only support auditory nerve survival, but promote regrowth of the nerve in the direction of the implant. Reducing the distance between the implant and the nerve it stimulates has multiple benefits for the cochlear implant user. Stimulation of regrown peripheral processes could lead to lower thresholds, longer battery life, increased number of independent channels, and a greater range of sound processing strategies. The proposed method of regrowth includes a novel combination of a conducting polymer, hydrogel, and growth factor implant coating that will not only provide a target for neurite growth, but also a supporting matrix on which optimal growth can be achieved.
Specific Aim 1 will assess morphological effects of this specialized coating by using immunocytochemistry to visualize neurite regrowth following implantation.
Specific Aim 2 will assess electrophysiological effects of the coating. The combination of anatomical and functional level measurement in an in vivo experimental protocol provides this proposal with both clinical relevancy to cochlear implant users as well as the potential to obtain a more complete understanding of the relationship between structure and function in auditory processing. Irreversible hearing loss can occur from a number of preventable and non-preventable sources, including aging, genetics, and environmental noise. The cochlear implant partially restores hearing to some deaf patients by stimulating the remaining auditory nerve, but the quality of hearing is not equal to that of normal hearing, especially for complex sounds such as speech in noise and music. This proposal aims to regrow the damaged auditory nerve to make contact with a cochlear implant through a specialized coating placed on the prosthesis prior tot implantation. The intent of this study is to improve the perception of sound from the implant and potentially provide the cochlear implant user with the ability to hear more complex sounds. ? ? ?
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