NRP Spring 2023. Darby Durbin: Cochlear Implants

When you think about neural implants, your first instinct is probably to picture the sensationalized Neuralink developed by Elon Musk. Musk proposes that this brain chip will allow the paralyzed to walk and the blind to see, even going as far as to claim that Neuralink will ultimately turn humans into cyborgs.¹ While Neuralink has not passed FDA approval, one neural implant device is already used by thousands of children and adults worldwide: the cochlear implant. Although it may not allow the blind to see or the paralyzed to walk as the Nuralink claims to do, the cochlear implant has pushed the bounds of scientific discovery by enabling the deaf to hear since the mid-1980s. 

Cochlear implants are suitable for those with severe or profound hearing loss. Before cochlear implants, it was widely held that people born deaf would never be able to hear, and those who suffered a traumatic injury to the inner ear would never hear again. Using electrical stimulation rather than acoustic stimulation, cochlear implants work by using an array of electrodes to directly activate the auditory nerve and produce the perception of sound in the brain. The cochlea itself is organized from low frequency to high frequency, with cells in the cochlea responding to specific frequencies. As such, each electrode of a cochlear implant represents a different frequency of sound, with the high-pitched electrodes at the base of the cochlea and the low-pitched electrodes situated at the tip of the cochlea. While the cochlear implant still doesn’t come close to what we consider typical auditory function, it can give a deaf person a useful portrayal of our auditory environment and aid in speech perception.

The cochlear implant has two components: an external part that rests behind the ear and an internal portion that is surgically implanted underneath the skin. The external hardware contains a transmitting coil, and the internal hardware contains a receiving coil. Communicating via magnets, radio frequency transmission between the transmitting coil and receiving coil is used to power the neural device and to dictate the type and level of cochlear stimulation. Initially, cochlear implants were only offered to postlingually deafened adults, or adults that acquired profound deafness after being able to hear during childhood. Current FDA guidelines now include cochlear implant candidacy for children with profound deafness as young as 12 months old. Cochlear implant candidacy primarily revolves around individual criteria such as medical status, whether the cochlear implant will provide more benefits than another artificial hearing device or even no hearing aid at all, and if the patient is in a supportive environment that will assist in rehabilitation and cochlear implant maintenance. In addition, individuals must undergo intensive speech therapy post-operation to learn or re-learn how to interpret sounds produced by the device. Much like a pair of glasses, this device is not one size fits all.

The cochlear implant device has made tremendous bounds in enabling a deaf individual to hear music again or recognize spoken language for the first time, but there are still many more improvements to be made and barriers to cochlear implant access that need to be addressed. The surgical implant of this device is expensive, and insurance might not cover it. Of the millions of people who would benefit from receiving a cochlear implant, only 6% of them have a cochlear implant.² Although different individuals will have various outcomes depending on personal history and the cochlear implant device selected, this neural implant offers deaf individuals a means of managing hearing loss that can vastly improve their quality of life. The field of audiology has taken center stage in recent years with the development of the first neural implant, and I cannot wait to see what comes next.

Sources:

https://www.nidcd.nih.gov/health/cochlear-implants

https://www.asha.org/policy/tr2004-00041/#:~:text=In%201984%2C%20Cochlear%20Corporation%20introduced,consisted%20of%2022%20banded%20contacts.

Works Cited:

1. Jewett, Christina, and Cade Metz. “Elon Musk Hopes to Test a Brain Implant in Humans next Year.” The New York Times, The New York Times, 1 Dec. 2022, https://www.nytimes.com/2022/11/30/health/elon-musk-neuralink-brain-device.html.
2. “Cochlear Implant Referral Criteria.” Cochlear, 8 Feb. 2023, https://www.cochlear.com/us/en/professionals/products-and-candidacy/candidacy/cochlear-implant-referral-criteria#:~:text=A%20cochlear%20implant%20may%20be%20the%20next%20step%20for%20your,they%20would%20benefit%20from%20them.&text=Conservative%20industry%20estimates%20suggest%20that,a%20cochlear%20implant%20have%20one.