What is a Cochlear Implant?

A cochlear implant is an electronic device. One part is surgically placed inside the inner ear while the other external part is worn behind the ear. The implant delivers electrical stimulation to the inner ear or cochlea and bypasses the damaged hair cells, directly stimulating the hearing nerve.

How Does a Cochlear Implant Work?

A cochlear implant is very different from a hearing aid. Hearing aids amplify sound. Cochlear implants compensate for damaged or non-working parts of the inner ear. In normal hearing, complicated parts of the inner ear convert sound waves in the air into electrical impulses. These impulses are then sent to the brain, where a hearing person recognizes them as sound. A cochlear implant works in a similar way. It electronically finds useful sounds and then sends them to the brain. Hearing through an implant may sound different from normal hearing, but it allows many people to communicate fully with oral communication in person and over the phone.

Criteria: Who is a Candidate?

Who is a candidate for a cochlear implant?

Children and adults who have severe or profound sensorineural hearing loss and derive minimal benefit from hearing aids may be candidates for a cochlear implant. According to the Food and Drug Administration 2002 data,approximately 59,000 people worldwide have received a cochlear implant; in the United States about 13,000 adults and 10,000 children.

The benefit that an adult receives from an implant depends on several factors: their degree of hearing loss, their ability to understand speech before receiving the implant, experience using a hearing aid, and the length of time they have been severely or profoundly deaf. Generally, the more experience a person has had with hearing and the shorter the duration of their deafness, the more benefit they can expect to receive. Benefits vary from excellent, the ability to understand speech without visual cues (as on the telephone), to minimal, the improved ability to lip-read.

Young children are excellent candidates for cochlear implantation because they have robust central nervous system plasticity, which allows them to make use of the sound the implant provides. Children implanted early, who do not have other significant developmental disabilities, and when coupled with intensive post-implantation speech and language therapy, may acquire age appropriate speech, language, developmental, and social skills. They are usually schooled in mainstream educational settings.

The best age for implantation is still being debated but research has clearly indicated that children who receive hearing early have the best results. The FDA, in 2002, lowered the age for inclusion in pediatric clinical trials to 12 months. However, many centers will implant children as early as six months if there is certainty as to the audiologic indications. In addition, the child must weigh about 20-22 lbs., which is important from an anesthesia viewpoint. Another indication for early implantation is bacterial meningitis causing hearing loss because the cochlea (the organ of hearing) will sometimes scar after meningitis, preventing implantation.

The evaluation process is a team approach. Obtaining accurate audiological information is at the core of making appropriate recommendations related to cochlear implant candidacy. It is important that the testing be done by a specially trained pediatric audiologist who is experienced in fitting and facilitating preimplant hearing aid use. The team also includes speech and language specialists, a social worker, an educational consultant and, of course, the operating surgeon. The criteria for implantation become:

• audiometric: is the hearing loss of appropriate degree and are hearing aids not sufficient?

• speech and language: what is the level of the child's present speech and language and what postoperative interventions are necessary?

• social work: to assure there is a stable family support mechanism and realistic expectations as to outcome

• educational: to plan for appropriate school placement to maximize learning

• medical: to be sure there is no contraindication to surgery such as chronic ear infections or abnormal inner ear anatomy

Implant Process

The first stage in the management of profound sensorineural hearing loss with a cochlear implant is proper assessment. This includes audiological, otological, medical, speech pathological and radiological evaluation. In addition, children who are being considered for implantation receive a complete speech and language evaluation and an assessment of educational support services available to them. These educational services are unique to the team and are performed by trained teachers of the deaf who visit each child's school before and after implantation. These services assure that children who receive implants can reach their optimal speech, language and educational skill level. Other tests may be required depending upon the needs of the individual. Throughout the entire implantation process, emphasis is placed on providing counseling and support for the adult or child being implanted, as well as their family members.

The surgery for the insertion of a cochlear implant requires an overnight hospital stay. After the operative wound has healed the implanted individual returns approximately one month later for the initial fitting of the speech processor and "turning on" of the device. Subsequent visits allow finer tuning of the processor.

For children, the Cochlear Implant Center Team provides an evaluation program and ongoing supervision through visits to the child's local school. Close contact is maintained with the local healthcare and educational professional who care for the child. We believe this "whole child" approach accounts for the long-term success of children implanted by the Cochlear Implant Center Team.

After Implementation

Individuals who receive a cochlear implant require continual follow up. Children, in particular, require a long period of rehabilitation to teach them to listen to the new sounds and to optimally tune the device. All children who receive cochlear implants can learn to hear the everyday sounds we take for granted. Most children are able to hear conversation without lip-reading and use spoken language for everyday communication. More than 75% of the adults are able to use the telephone for conversation.

Our approach is particularly unique with children in that we believe that follow-up by our educational consultants from the implant team is crucial to a child's long-term success. The Cochlear Implant Center serves children throughout a wide geographical area.

Benefits

Adults who have lost all or most of their hearing later in life can often benefit from cochlear implants. These older candidates can often associate the sounds made through an implant with sounds they remember. This may help them to understand speech without visual cues or systems such as lip reading or sign language.

Many young children can also be candidates for implants. Cochlear implants, coupled with intensive post-implantation therapy, can help young children to acquire speech, language, developmental and social skills. The best age for implantation is still being debated, but it appears that earlier implantation performs better. Most children who receive implants are between two and six years old. Because of research conducted at Beth Israel/New York Eye and Ear Cochlear Implant Center and other centers, infants as young as seven months old can now be implanted with cochlear devices.