What is a cochlear implant?
A cochlear implant is an electronic device that provides a sensation of hearing to individuals who are deaf. It does not provide "normal" hearing, but the device can allow children to detect and differentiate among sounds. It consists of two main parts: an external part worn somewhat like a hearing aid, and an internal part which must be implanted by a surgeon.
The external part of a cochlear implant is the speech processor. It has a "microphone" worn over or behind the ear. The microphone feeds the sound to the speech processor in the form of electricity. The speech processor codes the sound input into electrical signals which are sent back through a cord to the “transmitting coil,” a thin plastic piece about one inch in diameter containing a magnet placed on the side of the head behind and slightly above the ear.
The transmitter sends the signals across the skin to the internal part of the implant (the "receiver/stimulator"), which is under the skin. The receiver/stimulator sends the signals into the electrode array, which is a one-inch long wire surgically inserted into the inner ear. The electrode array consists of several electrode bands, each of which can provide a tiny current to the inner ear, to replace the function of the damaged or missing hair cells of the cochlea which ordinarily would stimulate the nerve endings of the auditory nerve.
Implants from different manufacturers differ in the number of channels, programming strategy, and appearance of the externally worn device. Behind-the-ear processors are available to eliminate the need for a body pack for many cochlear implant users.
Does a cochlear implant provide normal hearing?
No. A cochlear implant provides a limited sense of hearing in the implanted ear. However, most individuals with good language abilities can learn to use this sound to understand spoken language. Many cochlear implant users can learn to understand spoken sentences without looking at the person who is talking, particularly if there is no background noise. Many can also learn to use the telephone.
Who can benefit from a cochlear implant?
Children who were born without hearing, and children who lose their hearing can benefit from an implant. Adults and children who once had enough hearing to perceive the sounds of speech have an easier time learning to use the new sound through an implant, but many children who never heard sounds before can learn to understand speech using the implant, if they have good cognitive (learning) abilities.
What factors might favor or limit my child's benefit from a cochlear implant?
Most children who are implanted receive some degree of benefit. Goals and expectations for the outcome of cochlear implantation vary for different children, and are reviewed thoroughly with the family before the surgery. Factors which favor a beneficial outcome from a cochlear implant are:
- favorable cochlear anatomy
- a solid base of language development prior to surgery (age-appropriate)
- a high level of motivation and commitment on the part of the family to keep frequent appointments, maintain the device, and encourage listening skills
- an appropriate educational program which incorporates listening activities into the curriculum
- regular speech/language therapy given by a clinician with specific expertise and experience in the area of spoken language development in deaf children using cochlear implants
The benefit from a cochlear implant may be limited by a child's previous language deprivation or by a particular child's disorder in language acquisition skills. The anatomy of the child's ear and auditory nerve also may limit sound reception and clarity with an implant. Illnesses such as meningitis may also limit outcomes.
At what age should a child receive a cochlear implant?
Children may be considered for a cochlear implant as young as 10 months. A congenitally deaf child who is going to have a cochlear implant should have the surgery before the age of four years, or earlier if possible. This early implantation gives the child the best chance to learn to use sound while language skills are developing.
Some congenitally or prelinguistically deaf children who receive cochlear implants when they are older do not develop the ability to recognize speech with the implant, and ultimately may reject its use. However, a school-age deaf child who makes maximal use of hearing aids and who already uses spoken language may benefit from a cochlear implant.
Children who once had normal hearing or partial hearing, and then became deaf, may be implanted as soon as it is clear that the child’s hearing is not going to recover and that there is little or no benefit from a hearing aid. A period of observation and training may be advisable after a seemingly total loss of hearing, to observe any recovery and to determine whether a hearing aid will help before the final decision is made to have an implant. Older children and teenagers who lose their hearing should participate in the decision whether to have a cochlear implant.
Should my child receive one cochlear implant or two?
Depending on your child's hearing, our team may recommend receiving two implants at the same time, or we may recommend starting with one implant. This determination is made based on many things, and will be decided in conjunction with the parents (and child when appropriate). One cochlear implant provides greatly improved access to sound for most candidates with severe to profound hearing loss. Some implant users benefit from continuing to use a hearing aid in the other ear. If a hearing aid provides no benefit, the child may be considered for candidacy to receive a second implant, to have access to sound in both ears. Bilateral cochlear implant use improves the ability to hear speech in noisy places and some ability to determine the direction a sound is coming from.
Should my child use sign language with an implant?
The option of a cochlear implant usually is chosen for the purpose of providing access to spoken language acquisition. After implantation, every effort should be made to give the child reasons to listen, hear, and learn to speak. However, every child’s language abilities and preferences are individual. Some parents of children with cochlear implants choose to use only spoken language to teach their child to communicate. Other children who have cochlear implants use both sign language and spoken language to communicate. If a child deaf from birth has a hearing loss so profound as to be a candidate for a cochlear implant, then the use of sign language prior to implantation provides full access to language.
Following the implant, some children (particularly those who were older than preschool age at the time of surgery) remain primarily users of sign language, and many children gradually make a transition from using sign language to using spoken language. However, sign language should not be withdrawn from everyday life to “force” the child to learn to speak. During auditory learning therapy sessions when the child is playing listening games, spoken language is often presented without sign to encourage listening. Both the home and school environment should provide the child who has a cochlear implant with plenty of meaningful spoken language input and with reasons to want to listen and hear. However, even children who become primary users of spoken language with their implants can still benefit from the use of sign language in less-than-optimal listening conditions, for learning new concepts, and when their speech processor is turned off or not being worn. The commitment of the family to provide full access to language is a requirement for the emotional well-being of any deaf child, including the child with a cochlear implant.
How is the cost of a cochlear implant paid for?
Most health insurance plans cover the pre-implant candidacy evaluation, the cochlear implant device, hospitalization and surgery, and follow-up visits at the hospital. The family is responsible for yearly theft/loss insurance after the first three years, and usually must pay for a service contract for the processor after the initial three-year warranty expires. The early intervention program or school district is responsible to provide ongoing speech and language therapy, with consultations provided by the hospital staff. The family plays a strong role in advocating and arranging for speech and language therapy, provided by a clinician with specific expertise and experience in cochlear implant habilitation, to be coordinated with the educational program.
What range of hearing loss must my child have to benefit from an implant?
A child with profound hearing loss in both ears may receive a cochlear implant at a year of age. If the hearing loss is severe (70-90 decibels) rather than profound (>90 decibels), then the child should be at least two years old and hearing aids must be tried long enough to determine whether the child can perceive speech with the aids. If an older child is able to hear well on the telephone using hearing aids, a cochlear implant might not provide more benefit. The Cochlear Implant Program considers implantation of cochlear devices for children with:
- Severe or profound sensorineural hearing loss in both ears
- Sloping hearing loss with limited benefit from hearing aids
- Auditory dys-synchrony (auditory neuropathy)
How do I find out if my child is a candidate?
To find out if your child may be a candidate for a cochlear implant, call our program coordinator at 781.216.2250. When you call, you will be asked to fill out an intake questionnaire and to provide any relevant audiological, speech/language, educational and medical reports if these evaluations occurred outside Boston Children's Hospital. This information will be reviewed by our team, and will help us determine the most appropriate course of appointments to evaluate your child's candidacy for a cochlear implant.
How long does the evaluation process take?
Children frequently require multiple tests and meet with a number of specialists during the evaluation process, often requiring several visits. We will keep you informed of your child's potential candidacy along the way. It is our job to determine, from all possible perspectives, that a cochlear implant is truly a good option for your child.
What appointments and evaluations will my child have?
Over the course of the candidacy process, your child will meet with many members of our cochlear implant team, including:
An audiologist: The audiologist provides hearing testing, and an information session for the parents, family members, and caregivers to learn more about cochlear implants and our program. The audiologist, along with our program coordinator, will be your family's main contact with our program.
An otolaryngologist (ear, nose, and throat doctor): The otolaryngologist assesses your child from a medical perspective to ensure that a cochlear implant is an appropriate option. This may involve ordering specialized tests, such as CT scan or MRI, or blood work, to assess your child's anatomy and possibly the cause of the hearing loss. The otolaryngologist will also provide a surgical consult to give additional information regarding what to expect during and after surgery. The individual you meet at your child's surgical consult is typically the surgeon who would perform your child's cochlear implant surgery.
A psychologist: The psychologist assesses your child's cognitive function and general development. The psychologist helps ensure there is adequate family support and commitment, and that your child has access to an appropriate educational program. For older children, the psychologist can also help prepare the child for what to expect during surgery.
A speech-language pathologist (SLP): The SLP assesses your child's speech and language development. This can include sign or spoken language, as our SLPs are fluent in sign language. The SLP will also assess your family's access to aural rehabilitation ("listening therapy") services that must be provided following implantation, and can help your family secure services for your child when needed. They are also able to provide direct aural rehabilitation services when therapy cannot be established closer to home.
Other specialists, such developmental pediatrics, occupational therapy, genetics, ophthalmology, and neurology are available as needed for consultation.
What happens after the evaluation appointment?
After your child has completed all necessary evaluations and examinations, the team discusses their findings with each other, with the family, and with your child's primary care pediatrician and school when appropriate. If it is determined that a cochlear implant is an appropriate option for your child, and your family would like to proceed with implantation, our program coordinator will work with your family to set up a surgery date.
Surgery & Follow-Up
What appointments are necessary prior to surgery?
Once your child has been approved to receive a cochlear implant, you will be given a pre-operative appointment ("pre-op"), as well as a surgery date. Pre-op typically takes place approximately 2-3 weeks prior to surgery, and typically includes a consultation with the anesthesiologist, and additional blood work.
Also, prior to surgery, your child will need to have updated immunizations, including one for meningitis. Our program coordinator will work with your family to ensure that your child has what is needed to proceed with surgery.
What happens during surgery?
The surgery is performed under general anesthesia and takes three to five hours. The child stays in the hospital one night after the surgery, or longer if needed. One parent may sleep in the child’s hospital room. During the surgery, the receiver/stimulator and electrode array are implanted. An incision is made behind the ear for the surgeon to expose the area of the round window, a tiny membrane at the separation between the middle ear and the inner ear. Then the surgeon places the receiver/stimulator in a small area on the side of the head where the bone has been drilled thinner to make a place for the receiver/stimulator to fit, outside the skull but under the skin. The brain is not exposed or penetrated during the surgery. The electrode array is inserted into the inner ear, and the receiver/stimulator is fixed in place over the bone. Electrical recordings are made to show that the electrodes are providing stimulation. The skin is surgically closed over the implant. An X-ray may be obtained to verify the placement of the device. When the external parts of the implant are not being worn, the implant is not typically visible from the outside.
What are the risks of surgery?
The risks of anesthesia are the same as for any surgery. Surgery to the inner ear also carries the risks (although uncommon) of facial nerve paralysis, loss of taste sensation, dizziness, or ringing in the ear. The surgery may destroy any ability the individual may have had to hear with a conventional hearing aid in that ear. It is possible that at some point in the future, the implant may stop working and may need to be replaced in another operation.
How can I help prepare my child for surgery?
A psychologist will meet with you and your child to help you find ways to feel comfortable and positive about the opportunity to have the surgery. For a young child, playing with dolls, head bandages, doctors’ masks and hospital vocabulary are ways to prepare for the surgery. Play dates or emails with other children who already have cochlear implants provide familiar role models. The cochlear implant team gives the child a backpack of age-appropriate items and games to take to the hospital. The child is encouraged to express questions and concerns. Brothers and sisters often have their own anxieties about the surgery, and their questions should be addressed so that they can feel positive and supportive about the implant.
How soon will my child be able to "hear"?
Three to four weeks after the surgery, your child comes in for the first “stimulation” using the speech processor. Activation of the speech processor requires two two-hour appointments within one week. During these appointments, your audiologist will assess your child's responses to help determine how much current to program each electrode to deliver. The audiologist may also use neural response recordings to program the device to give sound sensations that are audible and comfortable. The program produced is called a "map", and appointments such as these are called "mapping" appointments. After the initial mapping, the child is seen for re-mapping and fine-tuning at:
one month post-activation;
three months post-activation;
six months post-activation (including hearing testing and a speech-language follow-along);
then every three months, typically for the first year or two.
What will my child hear when the implant is activated?
Because only the recipient knows what they hear through a cochlear implant, we have to rely on what they tell us about what it sounds like. Most older children tell us it sounds like static, or buzzing, or high-pitched squeaky sounds. Regardless, in most cases your child may not understand speech when the processor is first turned on. Months to years of listening therapy is typically required to help your child's brain make sense of the sounds it is receiving. This is especially true for children who are implanted very young, and for children implanted later with limited spoken language abilities. Please refer to the "Additional Resources" page for simulations of what science tells us a cochlear implant might sound like.