Cochlear Implants – FAQ’s
What Is a Cochlear Implant?
The cochlear implant is a prosthetic replacement for the inner ear (cochlea). It is a small, complex, multichannel electronic device that helps provide a sense of sound through electrical stimulation of the auditory nerve for hearing-impaired and deaf individuals. Though the implant does not restore normal hearing, the stimulation provides a wide range of auditory information needed for recognizing environmental and speech sounds to expand communication ability.
The cochlear implant bypasses damaged parts of the inner ear and electronically stimulates the nerve of hearing. The cochlear implant system consists of two parts:
- The internal part consists of wires that are surgically implanted into the cochlea through the skull behind the ear
- The external part consists of a microphone, a speech processor (that converts sound into electrical impulses), battery and some devices also have a connecting cable
How Does Natural Hearing Work?
To understand how a cochlear implant works, it is important to understand the structure of the ear and how it works.
Sound waves enter the ear canal and impact the ear drum (tympanic membrane). The ear drum transmits sound wave vibrations through the chain of three (3) middle ear bones made up of the hammer (malleus), anvil (incus), and stirrup (stapes). The stirrup passes the vibrations to the inner ear fluids within the cochlea. Fluid waves travel through two and a half (2½) turns of the cochlea, bending the cochlea hair cells as it goes by. The hair cells correspond to the frequency of the original sound waves, initiating signals within their corresponding nerve endings prior to sending them to the brain.
- Sounds enter the ear canal and travel to the eardrum.
- These sound waves cause the eardrum to vibrate, setting the bones in the middle ear into motion.
- This motion is converted into electric impulses by tiny hair cells inside the inner ear (cochlea).
- These impulses are sent to the brain, where they are perceived by the listener as sound.
How Does a Cochlear Implant Work?
A cochlear implant is designed to bypass damaged or degenerating cochlear hair cells (within the inner ear that correspond to the sound wave frequencies). The hair cells are the “spark plugs” of the inner ear nerve endings. The vast majority of deafness is usually the result of non-functioning hair cells, however, with the nerve endings still purposeful in the majority of those cases, it makes it possible for cochlear implants to work.
- The external sound processor captures sounds, then filters and processes the sounds.
- The sound processor translates the filtered sounds into digital information, which is then transmitted to the internal implant.
- The internal implant converts the digital information into electrical signals, and sends them to a tiny, delicate curl of electrodes that sits gently inside the cochlea.
- The electrical signals from the electrodes stimulate the hearing nerve, bypassing the damaged cells that cause hearing loss, allowing the brain to perceive sound.
Who Is a Cochlear Implant Candidate?
Individuals who receive little to no benefit from hearing aids are usually considered to be candidates for a cochlear implant. In other words, a cochlear implant can be considered when significantly better hearing ability can be achieved from a cochlear implant compared to the most optimally fitted hearing aids. Current cochlear implant technology works so well that the candidacy criteria is expanding rapidly. The following are generally accepted candidate criteria.
- Infants: 6 months or older with profound hearing loss in both ears
- Children: 2 years and older with severe to profound hearing loss in both ears
- Adults: 18 years and older with moderate to profound hearing loss in both ears
- Limited benefit from optimally fitted hearing aids with speech understanding test scores less than 50%.
- No medical contraindications
- High motivation and appropriate expectations
- Participation in an educational or training program that emphasizes auditory skills and oral communication
What Is a Hybrid Cochlear Implant?
A hybrid cochlear implant consists of a cochlear implant and a hearing aid. Hybrid models are used when a patient can benefit from a mix of the acoustic signal through the hearing aid and the electrical signal from the cochlear implant. Your audiologist will tell you if you are a candidate for a hybrid cochlear implant and the unique features of these implants.
What Is Involved in Cochlear Implant Surgery?
The procedure is performed under general anesthesia in a day surgery unit with most patients going home the same day. An incision is made in the crease behind the ear and a pocket is created under the skin to accommodate the receiver-stimulator portion of the implant. A very small opening is made into the cochlea to insert the implant electrode array. The incision is closed with hidden absorbable stitches that do not require removal.
Activation of the Cochlear Implant
The initial activation of the device and orientation to the external equipment takes place about 1 week after surgery. At that time, the patient will be fitted with the external parts of the device, which requires “programming” (also known as “mapping”) of the external speech processor by the audiologist. During this process, the patient will begin to hear his/her first sounds generated by the implant.
The programming of the external speech processor is a procedure that allows the implant system to be set to suit each individual’s needs. As an individual’s tolerance of sound improves with time, the implant stimulation levels can be adjusted. Recipients should be committed to returning for programming sessions frequently in the beginning of the process then bi-annually or annually thereafter. The Cochlear Implant Team is committed to continuing to work with each implant recipient to ensure optimal benefit from the device.
What Benefits Can Be Expected From a Cochlear Implant?
Cochlear implants are amazing, but they are not magic. They are only the beginning of a long, persistent journey toward the hearing world.
If our team has determined you are a candidate for a cochlear implant, this means that with the proper programming, hearing therapy, and time, you should receive more hearing benefit from a cochlear implant than you are currently receiving from a hearing aid. As a group, individuals with a cochlear implant are pleased with the benefit they receive.
Most patients do not recognize speech from the cochlear implant after it is turned on/activated. Instead, patients report hearing “chirps”, “beeps”, “slow drawn-out talking”, “unrecognizable talking”, “high pitch sound”, “rushes of air”, etc. With consistent use of the cochlear implant, programming, hearing therapy, and daily at-home listening practice, gradual improvement is expected. Progress in speech understanding can be measured with the passing months and even after one year of cochlear implant use.
The cochlear implant improves hearing but does not provide normal hearing. Sound quality and speech understanding will improve over time, not immediately. Things may not sound like you remember. Music quality may be poor.
Will I Be Able to Hear on the Phone?
About 50% of cochlear implant users can hear on the phone. The other 50% usually have good results using speakerphone or a captioned phone so that they can read the dialogue and hear the voice at the same time.
I Currently Have Tinnitus (Ringing in the Ears). Will a Cochlear Implant Fix That?
Sometimes tinnitus may be decreased by the cochlear implant but sometimes it may remain unchanged. It is rare that tinnitus becomes worse with a cochlear implant.
Am I Too Old for a Cochlear Implant?
Any patient who is in good health regardless of age can consider a cochlear implant.
Will Insurance Cover the Cost of a Cochlear Implant?
A cochlear implant is covered by most insurance companies and plans, including Medicare. Our insurance reimbursement specialists will work with your insurance company to determine your coverage towards a cochlear implant.
Which Device Should I Choose?
We are often asked by patients and parents, “Which device should I choose?” Our answer is always the same: “Any of them.”
The Center for Cochlear Implants is experienced with devices from all manufacturers (Advanced Bionics, Cochlear, MED-EL). We will work with the patient and/or their family to select the device that best meets their needs. Each of the cochlear implant devices are excellent devices with comparable electronic capabilities made by stable, well established companies. Patient performance with a cochlear implant is determined more by factors such as age, duration of hearing loss, amount of speech acquired before the onset of hearing loss, educational setting, amount of time with the implant, how hard patients and parents work in therapy after the implant, etc. It is crucial that patients/parents place their focus on these issues and not expect the device to guarantee a good outcome.
Should I Wait for Future Technology Instead?
We are also frequently asked, “Should I wait for future technology before proceeding with cochlear implant surgery.”
The answer is, “Absolutely not.”
The current generation of cochlear implant technology provides excellent auditory detail and can be upgraded to better technology in the future if warranted. The duration of hearing loss before implantation and conversely the amount of time an individual has been using an implant are two major determining factors in hearing performance. Each day, each month, and each year without an implant is time lost towards auditory integration and speech acquisition, especially in children who have a limited “window” of opportunity to obtain maximum benefit from an implant.
DO PEOPLE GET TWO COCHLEAR IMPLANTS?
Placing a cochlear implant in both ears has now become a standard of care for children and adults who meet certain candidacy criteria. The rationale for and benefits of bilateral cochlear implantation are complex. The Dallas Ear Institute is world renowned for its research in this field. Our surgeons and audiologists will discuss this possibility as part of your or your child’s comprehensive plan for restoring the best hearing possible in both ears.
Download Rationale for Bilateral Cochlear Implantation in Children and Adults
Download Importance of Age and Post-Implantation Experience on Speech Perception Measures in Children with Sequential Bilateral Cochlear Implants
Download Worldwide Trends in Bilateral Cochlear Implantation
Download Presentation at AAA 2010
What Is the History of Cochlear Implants?
The use of cochlear implants for the treatment of severe to profound hearing loss is one of the most revolutionary treatments of our time. Cochlear implant technology was developed over 30 years ago, based on the idea that profoundly hearing impaired individuals have remaining auditory nerve fibers that can be electrically stimulated to produce a sense of hearing.
Age of Research
In the early years of development, cochlear implants were very experimental. No one knew what the effects of electrical stimulation of the inner ear would be. It was apparent that a “sense” of hearing occurred with this stimulus. However, a great deal of experimentation would be needed to determine whether this could be used to restore useful hearing.
- What is the best way to “code” the complexities of sound into electrical pulses?
- Did it matter where the electrodes were placed inside the inner ear?
- What is the optimal number of electrodes?
- Would it work in children as well as adults?
- What are the effects of long term electrical inner ear stimulation on the hearing nerves and brain, especially in children?
Age of Acceptance and Expansion
With the advent of multichannel implants, particularly the Cochlear Nucleus 22, it soon became apparent that very useful hearing could be provided through electrical inner ear stimulation and could be done safely, even in children. As processing strategies became more advanced, even better hearing performance was achieved. For the first time in history, the prosthetic restoration of a human special sense was taking place. More and more patients of all ages could now benefit from this technology. The question of whether or not cochlear implants work was clearly answered with a yes.
Now the only question remaining was how well can they be made to work?
Age of Refinement
In the late 1990’s, new processing strategies, miniaturization of the processors, and advancement of postoperative aural rehabilitative therapy improved rapidly. The Cochlear Nucleus 24 was approved for implantation in children 12 months of age or older as it became apparent the younger a deaf child is implanted, the sooner the child will assimilate language. Implant performance improved so dramatically that adults who had some residual hearing but were performing sub optimally with hearing aids became potential cochlear implant candidates. Some adults were achieving word recognition over 90% with the implant.
- Advanced Bionics
There are over one million deaf individuals (those with profound hearing loss) in the United States. Over four times that number have severe hearing loss. Four thousand children are born deaf each year.
Outcome studies have shown cochlear implants to be one of the most cost-effective medical treatments of our day in terms of the long-term impact on a recipient’s quality of life relative to their cost, far greater than coronary bypass surgery or kidney dialysis.