Hearing

Technological advancements are allowing some individuals to hear. For some who have a desire to correct deafness, a cochlear implant can be a solution that opens up the world of sound, music and spoken words to individuals who thought they would never hear the sound of their loved ones’ voices.

Auditory devices: Cochlear implants bring the sound-filled world to individuals with hearing impairment

When a child has never heard sound, he or she is dependent on perceptions.

The child likely knows that he or she is loved, but has never heard the words “I love you.” From a practical standpoint, the child would not be able to hear a fire alarm, or a police siren. And, some of the most joyful sounds in life – laughter, music, or applause – would be entirely silenced by deafness.

Deafness on its own is a difficult disability to cope with. For children with Cerebral Palsy, deafness can further complicate a series of physical and cognitive issues that a child must continually strive to overcome. Deafness is a permanent condition that cannot be improved through therapy.

There is, however, an assistive device that can be a game-changer for anyone coping with deafness. The cochlear implant, which represents a significant advancement in the treatment of deafness, was pioneered in the early 1960s by otologist Dr. William House. It is a complex device that uses microphones, speech processors, transmitters and stimulators to send messages to the auditory nerve. This, in turn, allows the auditory system to sense sound.

The implant brings to people, depending on the completeness and nature of their deafness, the ability to hear and distinguish loud noises, and sometimes, enables recipients to hear and understand speaking.

An implant sounds like a godsend to parents, especially if a child also has blindness, or is mute. It’s a chance to give a child one of his or her senses that can compensate for the loss of others. But there are considerations that must be weighed. Like other surgeries, implantation also carries a risk.

What it is and how it works

A cochlear implant is a device designed for the severely hard of hearing and the deaf. It is made up of two parts – a small implant that is surgically placed under the skin of the ear and an external device that sits behind the ear.

The implant is not a hearing aid – which simply amplifies sound to understandable levels. It is comprised of a microphone, which picks up sound; a speech processor, which sorts out and organizes sounds to assist the person in discerning sound; a transmitter and receiver, which receives signals from a speech processor to convert them into electric impulses; and electrodes, that collect impulses and sends them to the auditory nerve. The receiver is in the part that is implanted behind the mastoid bone; the transmitter is in the external device.

The implant essentially bypasses portions of the ear that are damaged by stimulating the auditory nerve; which interprets the signals as sound.

A cochlear implant is installed while a person is under general anesthetic, and it usually takes up to two hours to complete. A child will likely be released from the hospital a day after the implantation.

After surgery, a child will not be able to hear immediately. He or she will need to wait at least three to six weeks for the wound to heal before being fitted for the external device, which will then be programmed. At this time, the child should be able to hear sounds.

Cochlear implants enable hearing by helping to organize sound. Sound received by the microphone is processed to determine which electrodes should be activated; pitch, volume and other considerations are sorted out. A process of filtering takes places that extracts sounds based on frequency, which also helps people interpret and understand sound.

The implants can be set to meet the needs of users, and an audiologist can set electrode levels for each user. The sounds a user may hear are different from traditional sound that is processed conventionally by the brain. Depending on a user’s condition and the reasons for their deafness, they may be able to hear only broad, distinguishable sounds, or they may be able to hear and understand words or music, and even speak and understand voices on the telephone.

It’s best to look at a cochlear implant as a compensatory measure for hearing, as opposed to a cure for deafness. The implants present a benefit to all people without hearing provided they are a good candidate for implantation – especially those with language skills that have progressively lost hearing.

Who can get an implant

According to the U.S. Food and Drug Administration, about 219,000 people worldwide have received cochlear implants. In the United States, 42,600 adults and 28,400 children have been implanted. Typically, a user will receive only one implant, but support is growing among researchers and physicians for the implantation of two devices.

In the United States, the age of implantation has been reduced by the FDA since the implant was introduced into the marketplace. A child can now receive and implant if he or she is at least 12 months old. Early implantation is recommended to give a child the best chance to develop language skills much in the same way other children do.

However, depending on how well a child can understand sounds, they may communicate using other visual cues including lip-reading and sign language. This is especially true because most children will receive an implant after they are four years old.

Because the success of an implant hinges on a child’s condition, physicians will look at several factors in determining whether a child is a suitable candidate for implantation. The factors include current language skills, levels of hearing loss or profoundness of deafness, a child’s overall health, and the ability of a child or family to be committed to post-implantation therapy.

An ideal candidate will have severe to profound hearing loss in both ears. He or she can receive maximum results if his or her auditory nerve is functioning.

Additionally, candidates who have had hearing loss for only a short period of time and have good communication skills tend to fare better than ones who has long-term deafness, as do those who have proper familial support.

Cochlear implants are not for children or adults with moderate hearing loss, as they can benefit from less complex and less invasive external hearing aids.

Infants that are congenitally deaf are viable candidates because they still have time to learn language skills, though older children often receive implants. Generally, older children require more services and supports to ensure a successful outcome. Children that are also blind can benefit from the surgery because it restores a sense that has been lost; it gives them an avenue to communicate and understand their surroundings.

Implant surgery is not a quick fix. There will be extensive follow-up care that is required for an optimal outcome. This involves meeting with audiologists to determine progress in terms of understanding sounds, and continuing to meet with speech language therapists to help children connect what they are hearing to speech and language.
Simply put, the work of hearing and understanding sounds doesn’t end with implantation.

Issues and concerns

Cochlear implants can have a revelatory effect on the lives of the people who receive the device, but that doesn’t mean there aren’t factors that need to be carefully considered before undergoing surgery.

Surgery is performed under general anesthesia, which does carry a small risk of injury or death.

Another factor is the cost of an implant. In the United States, costs can vary from $40,000 to $120,000; this cost is not always completely covered by insurance.

But the most significant factor to consider is to what extent a child can benefit from implantation. If a child is only likely to hear certain sounds, is it worthwhile to have the surgery? Is a child mature enough to be able to care for the implant, and will he or she be patient enough to meet with therapists and pediatric audiologists after the implantation?

Not every child realizes the same benefit or a positive result. Will the child be able to cope with a result that may be different from what they expected?

Other infrequent complications that can occur after surgery include the development of necrosis near the implant site, which can be treated with hyperbaric oxygen. Also, the cochlea is near several facial nerves, which can be injured during surgery. There is also an increased risk of meningitis, dizziness and vertigo, and blood and fluid collection at the surgery site. And all surgery carries the risk of infection. These issues are rare, and generally, implantation is considered safe.

Implant technology is constantly being modified and improved. Current research is being conducted to make implants more responsive to people with nerve damage or a non-functioning auditory nerve so that they can realize more benefits from this option.

When a child goes to the hospital for surgery, it is only after his or her parents have carefully weighed the benefits against the drawbacks. A cochlear implant is no different. Implants possess remarkable technology that can bring life-changing opportunities for a child. Whether implantation is the right course for your child, is a decision only you can make.

For more information on cochlear implants:

Food and Drug Administration – Cochlear Implant

The American Academy of Otolaryngology – Cochlear Implant

National Institute on Deafness and Other Communication Disorders – Cochlear Implant

NIDCD’s Directory of Otology Contacts