What Is a Cochlear Implant?
A cochlear implant is a surgically placed device that provides a person who has sensorineural hearing loss and receives limited benefit from appropriately-fit hearing aids with the ability to hear with more clarity.
Cochlear implants allow for improved sound awareness and speech understanding in both quiet and noisy environments.
After surgery, the cochlear implant settings are managed by an audiologist, who works closely with the patient and care team to provide optimal access to sound.
What Is the Difference Between Cochlear Implants and Hearing Aids?
A traditional hearing aid makes sound louder, and uses the entire hearing system (outer-, middle-, and inner-ear) to receive and pass the signal to the hearing nerve and on to the brain. The inner ear is filled with thousands of tiny, specialized cells. In sensorineural hearing loss, these cells can’t receive sound and send it to the nerve as needed into order to provide optimal clarity. A cochlear implant is surgically placed within the inner ear, inside the cochlea, and essentially takes the place of these delicate cells. The implant then sends electrical signals directly to the hearing nerve.
How Does a Cochlear Implant Work?
A cochlear implant is a two-part device. The external portion, called the processor, picks up acoustic sound. The sound processor is held in place over the implant with a magnet. The sound is then processed and sent via radio frequency signal to the internal portion. After receiving the signal, the internal portion sends it to the electrodes placed in the cochlea. The electrodes send small pulses to the hearing nerve which then sends the signal to the brain.
What Do Cochlear Implants Look Like?
Often, a cochlear implant processor looks like behind-the-ear (BTE) hearing aids with a cable coming off the back leading to a small round coil that is about the size of a half dollar. There are some off-ear processors available, which sit slightly above the ear on the head and are oval and slightly larger than a behind-the-ear coil. All external processors come in a variety of colors.
Who Is a Candidate for a Cochlear Implant?
Cochlear implants are an option when benefit from hearing aids is limited. It’s very important to understand that cochlear implants are NOT a last resort. They are an option when hearing aids aren’t providing as much benefit as a patient needs to hear and understand adequately. It is estimated that roughly 98 percent of people who could be good candidates for cochlear implants don’t have one (Nassiri et al, 2022), often because of the outdated belief that cochlear implants cannot be considered until someone has severe-to-profound hearing loss and no benefit from hearing aids.
Candidacy for a cochlear implant is determined by a team of providers and the patient and their family. When being evaluated for a cochlear implant, the following assessments and considerations are made:
Children
Typically, a child will minimally be evaluated by a pediatric audiologist; a pediatric otolaryngologist (ENT), otologist or neurotologist; and a speech therapist or auditory-verbal therapist. These assessments help the team determine the type and extent of the child’s hearing loss, the ability of hearing aids to help them obtain appropriate developmental milestones, and their medical candidacy for surgery. After all evaluation is completed, the hearing implant team determines if the child is a candidate for a cochlear implant and what to expect for each specific case.
At a minimum, evaluations will include assessment of the child’s speech and language development, a hearing assessment to determine degree of hearing loss, and evaluation of the child’s performance or benefit with hearing aids. Benefit may be evaluated by a parent questionnaire. The questions will determine if the child can respond to sounds while wearing their hearing aids. If the child is old enough, an audiologist will evaluate how well they can repeat back words or respond to sounds while wearing their hearing aids. Physicians will order imaging via either CT or MRI.
Children are candidates for cochlear implants when the hearing implant team determines that hearing aids will not allow the child to progress as needed to reach the family’s communication goals.
Adults
Typically, an adult will minimally be evaluated by an audiologist and an otolaryngologist (ENT), otologist or neurotologist. These assessments help the team determine the type and extent of the individual’s hearing loss, the ability of hearing aids to help them hear and communicate in their most common listening environments, and their medical candidacy for surgery. After all evaluation is completed, the hearing implant team determines if the individual is a candidate for a cochlear implant and what to expect for each specific case.
At a minimum, evaluation of candidacy will be completed by an audiologist and may include an assessment of hearing and with and without wearing well-fit hearing aids, including evaluating understanding of speech in quiet and in noise. An audiologist will evaluate how well the candidate can repeat back words or and sentences while wearing their hearing aids and/or hearing aids that have been programmed to their hearing loss for the purpose of the evaluation. There may also be questionnaires related to your difficulties and goals related to your hearing.
Physicians will order imaging via either CT or MRI and may also request vestibular testing to understand if one ear is more responsible for maintaining balance than the other ear. Because the cochlea is connected to the vestibular system, it’s important to understand whether the individual’s balance could be affected by the surgery.
Adults are determined to be cochlear implant candidates if the team believes that they will achieve more benefit from a cochlear implant than from a hearing aid.
How Much Hearing Loss Qualifies for CI?
Candidates for cochlear implantation generally understand less than approximately half of words spoken at a conversational level when wearing well-fit hearing aids. Candidates can have good hearing in the low pitches or in the non-candidate ear and still be considered an implant candidate. It is important to know that candidacy for cochlear implantation has expanded tremendously in recent years, making cochlear implantation a viable option for many more patients than ever before.
Unaided hearing tests, such as a traditional audiogram, do not predict cochlear implant candidacy well. The most straightforward candidates may be identified using the “60/60 guideline,” which suggests that individuals with an unaided PTA >60 dB and word understanding <60 percent should have a cochlear implant evaluation (Zwolan et al, 2020). This guideline does not capture all potential candidates, most notably excluding those with substantial residual hearing and single-sided deafness, so even patients who exceed this guideline but have limited benefit from amplification in one or both ears can be considered for CI evaluation.
FDA labeling for cochlear implants reflects the indications that have been submitted by implant manufacturers and approved by the FDA. However, implant teams can and do recommend implants for patients outside of these guidelines when evidence in the literature and their clinical experience suggests that patients will obtain benefit. Cochlear implantation is a covered benefit for most insurers, including Medicare; however, some insurances have strict coverage requirements that may meet or exceed FDA labeling.
What Is Cochlear Implant Surgery?
Cochlear implant surgery is typically an outpatient procedure performed by an otolaryngologist, otologist or neurotologist.
Prior to surgery, the implant team will ensure the candidate is up to date on any necessary vaccines.
During the procedure, the individual will be asleep with anesthesia. The surgeon will create an incision behind the ear and proceed to the middle ear space. Once in the middle ear, they will visualize the cochlea and create a small opening. The implant is placed on the skull and the electrode is slowly guided into the cochlea in the inner ear. Once this is complete, the surgeon or an audiologist will check the placement of the device with an x-ray or via some preliminary tests on the implant that also ensure it is functioning. These tests include impedances and evoked compound action potential testing. Surgery takes approximately one to three hours.
After surgery, most patients go home the same day and the ear is given some time to heal. One to four weeks after surgery, the cochlear implant gets “activated,” which is when sound is turned on and the device is programmed with an audiologist.
On this day, sounds are not usually clear—some people say they hear beeps and squeaks, while others say they hear robotic or cartoon voices. Over time, listening performance improves (Wilson and Dorman, 2008), but this process requires practice and effort. The biggest improvements are usually noted in the first one to three months, but it can take up to a year to achieve maximum benefit. Within the first year of having the implant, the recipient should return regularly to update the device settings with their audiologist.
It is important to remember that each person’s performance and experience can be different with a cochlear implant, depending on the cause of hearing loss (Blamey et al, 2013) and duration of hearing loss (Rubenstein et al, 1999). The audiologist will guide recipients through the entire process and can help establish realistic expectations and provide strategies for success for each individual situation.
Risks of cochlear implantation include:
- General anesthesia risks
- Injury to the facial nerve
- Meningitis
- Cerebrospinal fluid leak
- Perilymph fluid leak
- Infection of the skin
- Blood or fluid collection at the surgical site
- Dizziness
- Tinnitus
- Changes in taste
- Numbness around the ear
- Other unforeseen complications (Centers for Devices, 2021)
How Much Does a Cochlear Implant Cost?
Most insurance carriers, including Medicare and Medicaid, cover at least some costs associated with cochlear implants. However, each plan varies, so it is important to investigate the details of each policy for specific information.
How Long Do Cochlear Implants Last?
Internal cochlear implants are developed to last a lifetime.
External cochlear implant processors have a similar lifespan to a hearing aid—five to seven years.
Do You Need a Cochlear Implant? Ask an Audiologist.
If you use hearing aids and have significant difficulty communicating, ask your audiologist about cochlear implants.
References
Blarney P, Arndt P, Bergeron F, et al (1996). Factors affecting auditory performance of postlinguistically deaf adults using cochlear implants. Audiol Neuro 1(5):293–306.
Nassiri AM, Sorkin DL, Carlson ML/ (2022) Current Estimates of Cochlear Implant Utilization in the United States. Otol Neurotol 43. https://adulthearing.com/wp-content/uploads/2022/04/Nassiri-Current-Estimates-of-Cochlear-Implant-Utilization.pdf (accessed January 10, 2023).
Rubinstein JT, Parkinson WS, Tyler RS, Gantz BJ. (1999) Residual speech recognition and cochlear implant performance: effects of implantation criteria. Amer J Otolo 20(4):445–452.
Center for Devices and Radiological Health. (2021) Benefits and risks of cochlear implants. U.S. Food and Drug Administration. www.fda.gov/medical-devices/cochlear-implants/benefits-and-risks-cochlear-implants (accessed June 14, 2022).
Wilson BS, Dorman MF. (2008) Interfacing sensors with the nervous system: Lessons from the development and success of the cochlear implant. IEEE Sensors J 8(1):131–147.
Zwolan TA, Schvartz-Leyzac KC, Pleasant T. (2020) Development of a 60/60 guideline for referring adults for a traditional cochlear implant candidacy evaluation. Otol Neurotol 41(7):895–900.
