Understanding the benefits and risks
01 December 2019
When hearing aids aren’t enough
In most cases, hearing aids are all that are needed to alleviate the symptoms of hearing loss. Hearing aids amplify everyday sounds and make it easier to hear those around you. In more severe cases of hearing loss, the ear is not able to make sense of the amplified sound provided by a hearing aid, and it becomes necessary to bypass part of the ear entirely with an implantable hearing aid known as a cochlear implant.
A cochlear implant is made up of a sound processor (left) and an implantable unit (right).
What are cochlear implants?
Cochlear implants are for people with severe-to-profound sensorineural hearing loss. They bypass damaged hearing hair cells in your cochlea and restore transmission of sound to the auditory nerve. When the hearing cells in the inner ear die and cause sensorineural hearing loss, a cochlear implant can process external sound, bypass the damaged hearing cells, and deliver it to the auditory nerve and brain.
Cochlear implants are electronic devices with internal and external parts that work together:
- Internal implant: When the hearing hair cells (cilia) in the cochlea in the inner ear stop functioning, they can no longer transmit the sound picked up by the eardrum. An electrode inserted into the cochlea can generate the same kinds of electrical signals that the dead hearing hair cells previously transmitted to the auditory nerve and brain. The electrode array is implanted on the skull under the scalp, and its filament extends through the skull into the cochlea in the inner ear.
- External sound processor: To receive and process sound, the implant system uses an external sound processor with multiple microphones. It can look similar to a large, behind-the-ear hearing aid, but instead of amplifying sound waves, it converts them into electrical pulses that the implant sends to the auditory nerve. A wire from the sound processor attaches to a headpiece with a magnet that couples with the electrode array under the scalp. The speech processor and headpiece transmit digital signals through the scalp to the electrode array, through a process called electromagnetic induction.
Implant systems have internal and external components: 1) External microphones capture sound waves. 2) An external sound processor that sits on the ear converts the sound waves into digital signals. 3) The headpiece attaches magnetically to the implant that sits under the scalp, and through induction sends the digital signals through an electrode to the cochlear in the inner ear. 4) The internal electrode stimulates the auditory hearing nerve. 5) The hearing nerve sends impulses to the brain, which interprets them as sounds. (Source: Advanced Bionics).
Like hearing aids, the sound processors can be programmed to accommodate different listening environments. Cochlear implant manufacturers are also starting to integrate Bluetooth capabilities for streaming audio from music players and transmitting calls from your smartphone directly into the sound processors.
In the past several years there have been significant advances in implantation techniques as well as in the implants themselves. One of the most significant innovations is the hybrid cochlear implant, which preserves much of the recipient’s residual hearing. The hybrid implant is only inserted at the entrance of the cochlea, where the hearing hair cells that transmit high-frequency sounds are located. It stops short of the apex of the cochlea, where low-frequency sounds are created. A hybrid implant is designed for patients with normal low-frequency hearing, but with severe-to-profound hearing loss at high frequencies. The implant creates “artificial” sound at the high frequencies while the patient retains the ability to hear naturally at low frequencies.
What do cochlear implants sound like?
It’s impossible to know in advance exactly what your implant will sound like to you. Immediately after activation, the sound can be tinny, distorted, or seem far away. But as your brain adjusts to the new auditory inputs, sound becomes increasingly “normal.” After implantation, most people report constant, gradual improvements in the quality of sound as well as speech comprehension, sometimes over a period of many months.
Because the limited number of electrodes in the implant can’t compare to the thousands of hearing hair cells that previously performed the same function, it’s impossible to exactly replicate sounds. The sound processor focuses first on optimizing the frequencies required to understand speech. But because the limited number of electrodes in the implant can’t compare to the thousands of hearing hair cells that previously performed the same function, it’s impossible to exactly replicate sounds. For instance, music is much harder to follow than when you have normal hearing, because your brain doesn’t get as many inputs on pitch and tone as it got before the cochlea’s hearing hair cells stopped functioning properly.
Cochlear implant simulations
On the internet and on YouTube you can find simulations designed to give you an idea of what your cochlear implant might sound like. But the internet audio simulations only let you know how your implant might sound at a given point in time. They don’t communicate the improvement in sound over time. Therefore, a better way to imagine how things might sound may be to talk to people who have had extensive experience with them. They can describe how similar or different their hearing is now.
Who is a candidate?
Cochlear implants address one of the most common causes of deafness, sensorineural hearing loss. That’s when the cilia in your cochlea stop functioning properly. The cilia, or hearing hair cells, function as the nerve pathways from the inner ear to the auditory nerve. The implant bypasses the damaged cilia and transmits sounds to the auditory nerve and the brain.
But they will not work for everyone. An otolaryngologist, or ear-nose-and-throat (ENT) surgeon, needs to evaluate you to discover the nature and extent of your hearing loss and your general fitness for surgery. If you do qualify, you will most likely only have to undergo the implant surgery once for each ear. The internal implants are designed to last as long as you live.
Pros and cons of cochlear implantation
If you qualify, you still must evaluate all the positives and possible negatives.
- Because the implant destroys many if not all of the remaining undamaged hearing hair cells in the cochlea, the effects of the surgery cannot be reversed. Some people opt to wait on progress toward a potential future “cure” for sensorineural hearing loss. Genetic therapies that may restore damaged hearing hair cells have shown some promise. However, those therapies are still in the basic research stage and are not expected to deliver positive results for a number of years at minimum.
- Those who were born deaf and grew up as part of the Deaf culture, where sign language is the preferred form of communication, often don’t feel they want or need cochlear implants. Similarly, many people with severe hearing loss decide not to opt for an implant because they are comfortable getting by with a mix of hearing aids, speech-reading, and other forms of assistive listening.
For many patients, the “pros” outweigh the “cons” when the surgery has a positive outcome and they start to enjoy communicating more easily at home and work.
How severe must my hearing loss be?
If you have severe-to-profound hearing loss, and if your hearing aids are no longer helping you understand speech in everyday situations, you may be a candidate. An audiologist gives you a hearing test to determine the extent of your hearing loss. In the past, most people only got a single implant, even if they were deaf in both ears. In recent years, however, more insurance coverage has become available for bilateral implants in both ears. Surgeries for each ear are often done one at a time, but sometimes surgeries for both are done at the same time.
Cochlear implantation versus hearing aids
Many people who have benefitted from hearing aids continue to use a hearing aid in one ear after receiving an implant in the other ear. So it is not necessarily an either-or choice. Bimodal hearing assistance, with an implant for one ear and a hearing aid for the other ear, is becoming more common. The major implant makers have been improving their systems to enable communication and coordination between the hearing aid and the implant processor.
Help for single-sided deafness
Cochlear implants are also helpful for people who are deaf in one ear. People with single-sided deafness have a harder time understanding speech in normal listening situations than people with hearing in both ears. They also have trouble localizing sound. An implant that restores hearing to the deaf ear can help alleviate those problems.
Other kinds of hearing implants
You may have heard of other kinds of hearing implants. Bone-anchored hearing implants and middle-ear implants address other forms of deafness, especially conductive hearing loss.
- Bone-anchored hearing implants: When organs in the outer or middle ear are damaged or deformed, they sometimes fail to conduct sound waves from the air to healthy hearing hair cells in the cochlea. Your skull bone is a very efficient conductor of sound waves to the hearing hair cells in the cochlea in the inner ear. A small implant in your skull can collect sound and vibrate the skull in a way that transmits the sound waves directly to the cochlear.
- Middle-ear implants: The delicate bones and other organs in the middle ear transfer sound waves from the ear drum to fluid membranes in the cochlea that activate the hearing hair cells. When they are damaged or working improperly, an implant in the middle ear can sometimes help them perform.
Unlike cochlear implants, which remediate sensorineural hearing loss, bone-anchored implants and middle-ear implants are for conductive hearing loss. Because they are for people who have healthy hearing hair cells in their cochlea, they are not helpful for sensorineural hearing loss.
What is the best age for an implant?
Cochlear implantation can be performed successfully at almost any age. Babies as young as 12 months and seniors in their 80s and 90s all routinely undergo successful implant surgery. In fact, cochlear implants have become standard treatment for children as young as 12 months who were born with severe to profound sensorineural hearing loss. But treatment for recipients, especially aural rehabilitation required after implantation and activation, varies greatly depending on their age.
Here are some guidelines from the American Speech-Language-Hearing Association (ASHA) for children and adults:
They may work for adults who:
- Have severe to profound hearing loss in both ears
- Have found that hearing aids do not help them
- Have no other medical problems that would make surgery risky
- Want to be able to listen, speak, and speech-read
- Started to talk before they lost their hearing
They may work best for children who:
American Speech-Language-Hearing-Association (ASHA)
- Have profound hearing loss in both ears
- Were not helped by hearing aids
- Have no medical problems that would make surgery risky
- Will be able to get treatment to work on hearing skills
Babies who receive cochlear implants can often acquire language at the same rate as children with normal hearing. But speech-language therapy is recommended as is would be for any child with hearing loss. And those who lose their hearing as adults need to become accustomed to hearing sounds in a new way as their brain starts to “rewire” itself to better understand speech.
Cochlear implantation surgery
If you think you may be a candidate, it’s easy to learn more. Your audiologist may refer you to a cochlear implant center. The three leading manufacturers, Cochlear Ltd., Advanced Bionics, and Med-El, all provide lists of cochlear implant surgeons and surgical centers where you can be evaluated. Or you may contact an implant center yourself – Hearing Tracker’s database of hearing healthcare professionals notes the audiology practices that have an on-staff specialist in cochlear implants.
Who performs cochlear implant surgery?
Cochlear implant surgery is most often performed by an otolaryngologist, a physician who specializes in the medical and surgical treatment of ear, nose and throat (ENT) disorders. Your audiologist may refer you to a cochlear implant center. Or you may contact an implant center yourself. The three leading cochlear implant manufacturers, Cochlear Ltd., Advanced Bionics, and Med-El, all provide lists of cochlear implant surgeons and surgical centers where you can be evaluated.
The evaluation includes an extensive hearing exam, tests to determine the health of your vestibular system, and an MRI to ensure you are a candidate for the surgery. In addition to a surgeon, cochlear implant centers are staffed with audiologists trained in programming cochlear implant processors, and in providing support for patients as they become accustomed to hearing with the implants.
The surgery to implant the electrode takes several hours when you are under general anesthesia. But it is often straightforward enough to be done on an outpatient basis. After making a long incision behind the ear, the surgeon drills through the mastoid bone to the middle ear, locating a round window membrane on the cochlea where the electrode will be inserted. The surgeon excavates a well in the skull where the electrode array can be placed under the scalp, and then threads the filament end of the electrode into the cochlea.
Risks of cochlear implants
While cochlear implantation has extremely high rates of success, as with any surgery there are potential complications. There’s the potential for infection, and there’s a slim possibility that the body will reject the implant, or that poor placement of the electrode in the cochlea might impact performance. There are also facial nerves and blood vessels that need to be avoided. However, the surgery has become routine enough to be done on an outpatient basis, and outcomes have consistently improved over the years.
Implant surgery recovery
When you come to, your head is wrapped entirely in a white bandage. The surgeon may prescribe some painkillers and steroids to avoid too much swelling around the ear and scalp. During the recovery period, you have no hearing in the impacted ear. But healing is quick, and after a week or two, you return for a follow-up checkup by the surgeon and a visit to the audiologist, who is ready to activate your sound processor.
Sound processor activation and programming
In your first visit to the audiologist after implantation, you are ready to activate your sound processor. The audiologist, who has special training with cochlear implants, performs a test to make sure the implant’s electrodes are working. Your audiologist shows you how the sound processor, the rechargeable battery, and the headpiece work.
After attaching the headpiece to your head, the audiologist activates the implant. Initially you hear a series of beeps and other tones. But in short order you start hearing environmental sounds. And with luck you will even be able to hear and understand speech before you leave the office. Initially, voices and other audio sound “tinny” or artificial, but as your brain adjusts, they start to sound more normal.
Cochlear implant “mapping”
The audiologist also starts programming your implant system, a process called “mapping.” The audiologist sets volume and comfort thresholds based on your response to the new sounds you are hearing. There are also multiple programs available, just as with hearing aids. They let you change settings to suppress background noise, make it easier to hear someone’s voice on the phone, adjust volume, and more.
Some patients start to understand speech right away, while for others, speech comprehension requires a period of adjustment. During that period, aural rehabilitation exercises prescribed by your audiologist can be very helpful. Then in follow-up visits, the audiologist tests your comprehension levels and charts your progress. Many patients see gradual improvement in understanding speech over a period of months after implantation.
After experiencing the new sounds for several weeks, you return to the audiologist for a follow-up visit, where your processor is fine-tuned. You continue with future mapping appointments at a rate you and your audiologist determine, depending on how quickly you get comfortable with the system.
How well do cochlear implants perform?
Every year, performance improves. Better surgical techniques result in improved placement of the implant to deliver better sound through the cochlea. The implants themselves have improved, with smaller and more efficient electrodes. And sound processor technology constantly improves, especially with new smartphone connectivity options.
Cochlear implant improvements
Outcomes have improved for infants and children born deaf, who acquire language and speech understanding capability at faster rates than in the past. Outcomes have also improved for adults, who enjoy more natural sound and higher rates of speech comprehension. Cochlear Ltd. has done extensive research on how well the implant systems work:
“Studies show adults with cochlear implants understand sentences on average almost seven times better than they could with hearing aids. Additionally, adults hear nearly four times better in noisy environments than with hearing aids…. Cochlear implants are designed to help a child develop speech, and research shows those implanted early in life have speech performance scores closest to scores of normal hearing children.Source: Cochlear Ltd.
Sound processor technology has also improved. Bluetooth connectivity to smartphones and interaction with hearing aids on a bi-modal basis have provided dramatically improved patients’ ability to communicate in everyday listening situations, including with the phone.
Cochlear implant failure rates
Implants experience two main types of failure, one relatively common and the other extremely rare.
Failures to external components are relatively common. Wires from the processor to the headpiece can fail, as can the tiny microphones in the implant processor. A breakdown of the external processor itself is less frequent. But when it does fail, it can be replaced quickly and very often under the manufacturer’s warranty.
Failures of the internal implants themselves are much less frequent. Various studies have shown percentage failure rates in the low single digits. But when an implant does fail, it’s a bigger problem than failure of external parts. Removal of the faulty implant and replacement with a new one is a standard course of action. That means another major surgery. There is also a risk the new implant won’t work as well as the old. However, with improved surgical techniques, outcomes providing the same level of hearing experienced previously are more common.
Life with cochlear implants
Life with implants is similar to life with hearing aids. They must be kept clean and dry. You need to take special steps to secure them when exercising, or if at work you must move around or sweat a lot. Swimming is possible, but only with special waterproof accessories. And the batteries need regular recharging. Here are some tips on living with cochlear implants.
Implants and sleeping
When you take off your sound processor to go to sleep, it leaves you completely deaf in that ear. You need to use a bed-shaker alarm clock that vibrates rather than rings. Also consider investing in a smoke alarm that can wake you with a strobe light instead of a high-pitched tone, which you won’t hear. And when traveling, be sure ask for hotel accommodations that include the strobe light fire alarm.
Implants and swimming
The major implant manufacturers provide both waterproof sound processors and waterproof accessories that keep the processor dry while swimming.
Cochlear implants can be used anywhere. The round headpiece on the child's head connects with a magnet to the implanted electrode array under her scalp; the pink external sound processor sits on her ear in a waterproof case for use in the tub or pool. (Source: Cochlear Ltd.)
Implants and flying
You can wear your sound processor on an airplane without having to turn it off. And you can wear it as you proceed through security checks.
Implants and diving
If you like scuba diving or sky diving, you will need to check with your doctor. Implant recipients are discouraged from going to deep depths where water pressure on your ears is very high, or from skydiving from heights where air pressure changes very quickly. Either situation can stress your vestibular system and create pressure on the implant, which might affect its performance. However, given ongoing improvements in the surgery, it’s worth consulting with your surgeon on current guidelines.
Implants and sports
You can participate in nearly any sport with a cochlear implant. However, if you sweat excessively you may have to use one of the waterproof options. You should also avoid contact sports that might result in a head injury that could damage the internal implant.
Implants and MRI’s
Given the huge magnetic field generated by an MRI machine, the presence of metal or a magnet nearby can have terrible consequences. For that reason, until recently patients with cochlear implants could not get MRI’s. The machine can start to pull the magnet in the implant out of the patient’s head, causing extreme pain and potential damage to the implant. However, new versions of implants are addressing that problem, so many patients who have been implanted very recently are able to undergo MRI’s without a problem. It’s important to find out from your surgeon or audiologist whether your implant is MRI safe.
Sound processors can be regularly upgraded, either with software updates or new generations of hardware. The implant manufacturers make sure to keep the upgrades compatible with your implanted electrode, which is designed to stay in your head for life. If you’ve worn hearing aids and upgraded them in recent years to obtain Made-for-iPhone capabilities, audio streaming, control with a smartphone app, or other enhancements, you will have similar opportunities with your cochlear implant processor.
The major suppliers offer long-term warranties (up to 10 years) on their internal implants, and shorter multi-year warranties on the external processors.
Using implants with the phone and TV
You can get an implant processor with a telecoil that works exactly the same way it does with a hearing aid. A t-coil transmits the phone signal directly without re-amplification. The latest generation of implant sound processors feature smartphone and Bluetooth connectivity for audio streaming of phone calls and music. And all the implant makers offer 2.4 GHz audio transmission of audio through an accessory streamer from remote microphones and from your TV.
How much do cochlear implants cost?
Implant surgery, plus the associated sound processor and other equipment, can cost anywhere from $30,000 to $100,000 for each ear. Most surgeries are covered by health insurance.
Insurance coverage is now available for a broader range of cases. If you are not yet profoundly deaf but suffer from severe, progressive hearing loss, and if your hearing aids no longer help you understand more than half of what you hear, you may already qualify for insurance coverage. In the past, insurance would only cover an implant for one ear, but now Medicare and private carriers often cover implantation for both ears. Medicare also offers reimbursement for replacement of batteries yearly and for a sound processor replacement once every five years.
Accessibility and awareness
Cochlear implants have helped hundreds of thousands of profoundly deaf people connect with the hearing world in more than 30 years since the U.S. Food and Drug Administration (FDA) approved them for use. In that time, there’s been constant improvement in outcomes, to the extent that many implant recipients can understand speech nearly as well as others with normal hearing.
While as accessibility has grown dramatically, awareness of the benefits of cochlear implants—and who qualifies for them—has lagged. According to cochlear implant industry leader Cochlear Ltd., nearly two million Americans are potential candidates, but only 5% of patients who might benefit have been treated.
Cochlear implant companies
There are three brands of implants with significant global market share.
- Cochlear Ltd., based in Australia, is the world leader with more than 50% global market share. It also manufacturers the BAHA bone-anchored implant
- Advanced Bionics, based in the U.S., is a subsidiary of Sonova Group, the world’s leading manufacturer of hearing aids.
- Med-El, based in Austria, has global distribution and also manufactures bone-anchored hearing implants and middle-ear implants.
Advanced Bionics and Med-El have approximately the same size market share, behind Cochlear Ltd. And Demant A/S of Denmark, one of the world’s top five hearing aid manufacturers, has recently started producing its own cochlear implants alongside its Oticon Ponto bone-anchored hearing implants. The Demant cochlear implant is still awaiting approval for use in the U.S.