A cochlear implant is a small electronic device that helps people hear. It can be used for people who are deaf or very hard of hearing. A cochlear implant is not the same thing as a hearing aid because it is surgically implanted and works in a different way.

There are many different types of cochlear implants. However, they are usually made up of several similar parts. One part of the device is surgically implanted into the bone surrounding the ear (temporal bone). It is made up of a receiver-stimulator, which accepts, decodes, and then sends an electrical signal to the brain.

The second part of the cochlear implant is an outside device. This is made up of a microphone/receiver, a speech processor, and an antenna. This part of the implant receives the sound, converts the sound into an electrical signal, and sends it to the inside part of the cochlear implant.

WHO USES A COCHLEAR IMPLANT?

Cochlear implants allow deaf people to receive and process sounds and speech. To a certain degree, they are devices that allow deaf people to "hear." However, it is important to understand that these devices do not restore normal hearing. They are tools that allow sound and speech to be processed and sent to the brain.

The way candidates are selected for cochlear implants is changing over time as the technology changes, and our understanding of the brain's hearing (auditory) pathways improves.

Both children and adults can be candidates for cochlear implants. They may have been born deaf or become deaf after learning to speak. Children as young as 1 year old are now candidates for this surgery. Although criteria are slightly different for adults and children, they are based on similar guidelines:

1. The patient should be completely or almost completely deaf in both ears, and get almost no improvement with hearing aids. Anyone who can hear well enough with hearing aids is not a good candidate for cochlear implants.
2. The patient needs to be highly motivated. After the cochlear implant is placed, they must learn how to properly use the device.
3. The patient needs to have reasonable expectations for what will occur after surgery. The device does not restore or create "normal" hearing.
4. Children need to be enrolled in programs that help them learn how to process sound.
5. In order to determine if a patient is a candidate for a cochlear implant, the patient must be examined by an ear, nose, and throat (ENT) doctor (otolaryngologist). Patients will also need specific types of hearing tests perfomed with their hearing aids on. This may include a CT scan or MRI scan of the brain and the middle and inner ear.
6. Patients (especially children) may need psychological evaluation to determine if they are good candidates.

HOW IT WORKS

In a normal ear, sounds are transmitted through the air, causing the eardrum and then the middle ear bones to vibrate. This sends a wave of vibrations into the inner ear (cochlea). These waves are then converted by the cochlea into electrical signals, which are sent along the auditory nerve to the brain.

A deaf person does not have a functioning inner ear. A cochlear implant attempts to replace the function of the inner ear by turning sound into electrical energy. This energy can then be used to stimulate the cochlear nerve (the nerve for hearing), sending "sound" signals to the brain.

Images

Ear anatomy

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Cochlear implant Prevention

Review Date: 05/31/2011
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine; Seth Schwartz, MD, MPH, Otolaryngologist, Virginia Mason Medical Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)