A cochlear implant is an implanted electrode device designed to create useful hearing for a person with a total or severe hearing loss. Deafness caused by nerve damage in the inner ear can be supplanted by surgically inserting an electrode array that will replace the missing or damaged nerve hair cells stimulating the precise site on the cochlea and sending signals to the brain’s auditory center and giving the recipient the sensation of sound.
Cochlear implants consist of two parts, the first part is the external sound processor which looks like a behind-the-ear hearing aid or the newer models which look like a large coat button which rests off the ear. Both of these styles connect to the internal processor by a magnet that is inserted under the skin during the surgery. The external processor contains the microphones and a battery similar to a hearing aid and a processor which converts sound to a digital format.
The second part is internal processor contains another thin processing unit and a thin wire with electrodes that is surgically implanted in the cochlea during an outpatient procedure. The internal part of the cochlear implant does not contain a battery or any power source. It is powered by the external processor via the antennas which surrounds the magnets.
In the healthy ear, sound travels through the outer ear (called the pinna) and travels down the ear canal where it reaches the ear drum in the middle ear setting it in motion with vibrations. If the outer ear or the canal is blocked by a malformation or even excessive ear wax, hearing can be affected. In this case, the cochlea may be perfectly normal but sounds can’t reach it.
After setting the ear drum in motion, sounds are enhanced by the three small bones that are connected to the far side of the ear drum, the last bone is called the stapes and it is attached to the oval window, a tissue covering the entry to the fluid filled cochlea.
Inside the cochlea, the vibrations caused by the oval window set 30,000 hair cells in motion depending on the volume and pitch of the sound. In turn these hair cells fire signals to the auditory nerve which transfers the signal to the brain and those signals are interpreted as meaningful sounds. Inside the cochlea, there are two types of hair cells and depending upon which ones are malfunctioning, the type of hearing loss is might be affected. The cochlea is tonotopic. This means the hair cells are arranged spatially and sounds of certain frequencies that are close to one another might be represented topologically in neighboring areas. In other words, the ability of a cochlear implant to have an enormous range of tones to bring back natural sounding hearing is possible.
If these hair cells are damage or missing then hearing loss or deafness occurs. A more precise explanation of the different types of deafness or hearing loss follows below.
Your specific type of hearing loss will help the audiologist/Otologist/NeuroOtologist determine the exact electrode array to use. The recipient does not choose this part.
There are two basic types of hearing losses, Conductive Hearing Loss and Sensory Hearing Loss. There are variations within these two categories as well.
Conductive Hearing Loss occurs when, as mentioned before, there is a malformation of the outer ear or the ear canal. Excessive wax build up can also prevent sound from reaching the ear drum. Ear wax can be removed by a hearing professional or trained audiologist. Conductive hearing loss can also be caused by excessive fluid behind the ear drum thereby restricting its ability to vibrate and move the bones of the inner ear. The middle ear bones might have an abnormal growth called otosclerosis. This growth restricts the stapes from functioning normally with the oval window, the tissue which it is attached to connecting the vibrations from the middle ear to the cochlea. The result is reduced hearing.
In severe cases tumors might prevent the middle ear from functioning.
These conductive losses can often be alleviated with surgery or simply the removal of ear wax. In all these cases the hair cells within the cochlea are normal or functioning fairly well, but the sound vibrations cannot reach them.
When the inner ear is functioning but the middle or outer ear cannot be repaired, there is a different type of cochlear assistive device called a baha(bone anchored hearing aid) We will talk about this in a later section.
Sensory Hearing Loss occurs when the hair cells within the cochlea are missing or damaged. There are two types of hair cells within the cochlea and depending on which ones are malfunctioning, the type of hearing loss might be affected. Most commonly, the hair cells which operate for higher pitch sounds are the most vulnerable. This is why many people lose the ability to hear higher frequency sounds first. Hair cells can be damaged by illness or disease, excessive loud noises, degenerative conditions and genetics.
Combination Hearing Loss can occur in some cases where both types are effecting some aspect of hearing.
In all cases only a professional hearing exam can determine the type of loss and the choices for restoration of hearing. Most people with a hearing loss with do fine with hearing aids. Other need the option of a cochlear implant or a baha. In the next section we will discuss the differences between how a hearing aid works vs a cochlear implant.
A hearing aid is designed to amplify sounds. If the middle ear need a boost in vibration to operate better or if the cochlea is damaged but operating at a reduced level, a hearing aid’s amplification might be sufficient. In other cases, boosting the volume of sound will not improve comprehension. This is why often those with a moderate to severe hearing loss notice they can hear sounds but have no idea what people are saying. A hearing aid at this point cannot improve comprehension and the ENT or audiologist will probably suggest that you consider a cochlear implant. In all cases a non-surgical method must be tried first. Cochlear implants require surgery. All other avenues must be exhausted first.
Cochlear Implants receive sound through their microphones and interpret it into digital format. Those signals are then sent to the internal processor, which has been surgically implanted, via antennas which surround the two magnets on either side of the skin in an area behind the ear. That signal is then processed again by the internal part of the implant and sent into the cochlea via a thin wire which contains electrodes. These electrodes fire in a sequence determined by the sound received and the nerve endings in the cochlea then send the signal to the brain which interprets it into useable sound be it speech, music or environmental sounds such as laughter of children, birds, traffic, sporting events or any sounds you have been missing for a long time.
Baha is used as mentioned above when the cochlea is fine but the outer or middle ear no longer functions. It is sent via vibrations through the skull. It is anchored with any one of several types of attachments. It is the only type of cochlear device that can be tried without surgery if a person is a candidate for it. Bahas will not work with nerve deafness. The cochlea hair cells must be intact.
Hybrid Cochlear implants are a combination of a regular cochlear implant along with an acoustical component that acts like a regular hearing aid. It is only used in a when a candidate suffers a very specific type of hearing loss in which there they still retain a high degree of low frequency hearing but they are missing the higher frequencies. Again, only a hearing test can determine if a person is a candidate for a hybrid cochlear implant.
Bimodal is a term used to describe any two different modes of hearing. For example, a cochlear implant on one side and a hearing aid on the other the other or a baha on one side and a cochlear implant or hearing aid on the other. Any combination using two different devices is considered bimodal.
Your first step is to locate a clinic or hospital that can do testing to determine if you are a candidate for a cochlear implant. They should be specifically qualified for testing cochlear implant candidacy. Hearing aid dispensers are not qualified to do this. There is a series of tests that can determine your qualifications. If your spouse or friend is reluctant to be tested but you know they are having a serious loss of hearing and withdrawing into isolation, don’t give up. See the section on How do I find an audiologist?
Because there are so many unknown factors about the causes of tinnitus, it is not possible to guarantee the results but many, many recipients report that their tinnitus was great reduced to the point they could ignore it after being activated.
In any medical procedure there is no guarantee, whether it is a knee replacement or a pacemaker or a cochlear implant. Cochlear implants have a very high rate of success and there are several factors which can determine the chances and degree of restored hearing a recipient receives:
· How long the person has been deaf? Generally those who have been deaf for a short time do better but there are many who have been deaf for decades who are very successful with restored hearing. Some who have been in total silence as long as 40-50 years do very well upon activation.
· Did the person become deaf before they learned to speak? How old were they when they lost their hearing? Younger people tend to do better but there is no rule. Age is not a factor in deciding candidacy for a cochlear implant.
How long were they using hearing aids before they lost their residual hearing?
· How dedicated is the recipient is to devoting time to hearing rehabilitation? How much support system do they have?Although it helps to have someone to work with you for hearing rehabilitation after you are activated with your cochlear implant, it is not critical. Many recipients live alone and use exercises designed for them.
· A person’s communication skills and cognitive abilities.
· In rare cases, the depth of the implanted electrode and other factors that may not be visible to the surgeon until the operation begins.
I have been told I have nerve deafness and there is nothing that can be done or a cochlear implant will not work for me.
This is a common misconception that the term “nerve deafness” implies the hearing nerve that connects the cochlea to the hearing center of the brain has been damaged or destroyed and a person is doom to live in silence the rest of their life. Many people, told by a well-meaning but uninformed general practitioner, harbor this misconception for years and never seek help.
Nerve deafness is the damage to the hair cells within the cochlea. This is exactly what the cochlear implant is designed to remediate. We have experienced this time after time, that a candidate has been told there is no hope for them yet either found another audiologist who understood the benefits of a cochlear implant or in some cases ignored their ENT doctor and went on to have successful surgery and activation. No, does not necessarily mean, no.
At either end of the spectrum, the oldest recipient was 102 years old and the youngest was 3 month old. There is no limit as long as the recipient is healthy.
All surgery involves a degree of risk. There are always considerations about the effects of anesthesia, balance and unforeseen circumstances. In rare cases, there is an effect on taste sensation which goes away in weeks or months.
The loss of residual hearing, if there is any in the implanted ear, is always possible but with improvements in the implanted electrode array and surgical technical techniques, this is becoming less common. This is a topic to discuss with your surgeon.
Surgery is outpatient. Unless there are unusual circumstances you will be on your way home the same day. Surgery itself generally takes less than two hours. You are sent home with a protective covering over your implanted ear that you will remove in 24-48 hours. As with any surgery, you will receive post-op instructions regarding keeping the stitches dry and how to deal with any post-op discomfort.
There is some restriction about lifting and bending for a week or so while the cochlear implant array sets in place in the cochlea. A week after surgery you will revisit your surgeon to have an external examination of the surgery site.
Many people are driving or partaking in their usual activities within a week.
Depending on your type of employment, it might be two weeks or less. If you are wearing a hearing aid on the non-implanted side you should be able to function well. Generally, you will be totally deaf on the implanted side until you are activated.
Two to four weeks after surgery, at your audiologist’s office, you will receive the external component of your cochlear implant and your audiologist will then put it in place and activate it.
Everyone’s activation day is different. Some will understand speech and sounds immediately. Most will not. It will take several days, weeks or months. A cochlear implant is not a magic bullet. It will require a certain amount of positive attitude, rehabilitation and patience. Your brain needs to learn to hear again. It’s important to keep your eye on the prize of restored hearing.
A cochlear implant is not worn while you sleep. Your brain needs to rest as does your skin/scalp where the magnet rests. The sound processor can be simply removed just as eyeglasses. It is simple, fast and becomes second nature. Many people forget they are wearing it and have entered the shower with it on. Not to worry as most are water resistant and recipients make this mistake only once.
I have heard the sound is mechanical. I don’t want listen to sound that seems like it is coming from a machine. I don’t want to lose the fidelity of music.
While the quality of sound from a cochlear implant may have been less than ideal decades ago, because of the improvements in technology this is no longer true. While upon activation, voices will sound like Mickey Mouse or R2D2, this effect will dissipate with time and sounds will be as natural as you remember them from the time you had normal hearing.
Music will take a bit longer to sound natural. It is the nature of the complexity of music. Cochlear implants are first designed to restore comprehensive speech and second for music.
There is no way to predict. It depends on many factors as we mentioned before. There is one thing that almost always helps the process, rehabilitation. The more you listen, the faster and better the results.
Receiving cochlear implant surgery and then being activated with the external processor does not result in instant restored hearing. Just as receiving a hip replacement, does not mean you can walk immediately. One needs to work at rehabilitation.
In the case of a cochlear implant there are listening exercises. Your audiologist will recommend some and others will be found online. Some you can do with a hearing partner who can read to you and you can repeat back what you heard. Other exercises can be done alone on your computer or smart phone. Patience and persistence are the keys to success.
For many of us, the years of struggling to use a telephone ended with receiving a cochlear implant. Almost all cochlear devices have a way to direct stream to a cell phone or a Bluetooth phone at home or in the office. It will take practice. The day will come when you can fearlessly make the calls you have been depending on other to make.
An active sports lifestyle is not a reason to disconnect from the world of sound. Many cochlear external processors have a high degree of moisture and dust resistance. Biking, running, swimming (with the appropriate waterproof case) or tennis and more are all possible while wearing your cochlear implant.
Unlike hearing aids, which generally are not covered, cochlear implants are classified as durable medical devices and are covered by insurance and Medicare. Most cochlear implant companies have departments to help you navigate the insurance issues.
Depending on your coverage there may be some but in most cases insurance will cover the vast majority of the costs.
All the makers of cochlear implants have suggestions for local clinics on their website.
Another source is the ACI Alliance website. acialliance.org
Castleconnolly.com is another source to find top ENT doctors who specialize in cochlear implants.
This is just a short list. Your local hospital might recommend others.
· Cochlear cochlear.com
· Advanced Bionics advancedbionics.com
· MedEl medel.com
· Contact cochlear implant manufacturers
· There are support groups for cochlear implant users. All the manufacturers have support groups both online and local meetings.
· Organizations that supply information about hearing loss such as the Hearing Loss Association of America, HLAA.com
· YouTube videos about various hearing topics
If you have more specific questions, please write us at firstname.lastname@example.org