Cochlear implants

How is a cochlear implant put together?

The external part of a cochlear implant is the speech processor. It has a "microphone" worn over or behind the ear. A cord leads from the microphone to the speech processor. The speech processor codes the sound input into electrical signals which are sent back to the "transmitter," 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.

In turn, 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 an array of 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 which ordinarily would stimulate the nerve endings of the auditory nerve.

Will a cochlear implant provide normal hearing?

A cochlear implant provides a limited sense of hearing. However, a cochlear implant combined with visual cues usually let most people understand spoken language.

Who can benefit from a cochlear implant?

Adults and children who used to have normal hearing or partial hearing—who learned to talk before they became deaf—often benefit from a cochlear implant.

If your child was born deaf or became deaf before he or she learned to talk, cochlear implants can also help. It just might take longer for them to understand spoken language.

What range of hearing loss must my child have to benefit from an implant?

To be a candidate for a cochlear implant, your child must have a severe or profound sensorineural hearing loss in both ears.

The average hearing level in the speech frequency range (500-2000Hz) must be poorer than 70 decibels in both ears without hearing aids, and with hearing aids your child must not be able to recognize single words clearly out of context without looking at the talker's face.

If your child is younger than 2, her hearing loss must be 90 decibels or greater in both ears.

At what age should my child receive a cochlear implant?

The Food and Drug Administration allows cochlear implants for children beginning at age 12 months. A congenitally deaf child who is going to have a cochlear implant should have the surgery before the age of four years, earlier if possible. This early implantation gives your child the best chance to learn to use sound while language skills are developing.

Children who once had normal hearing or partial hearing, and then became deaf, may be implanted as soon as it is clear that there's no benefit from a hearing aid.

What factors might favor or limit my child's benefit from a cochlear implant?

Ask yourself and your physician:

• Does my child have good cochlear anatomy?
• Does my child have good underlying language abilities?
• Did she have a solid base of language development prior to surgery?
• Will we participate in regular speech/language therapy given by a cochlear-trained clinician?