Cochlear Implant (CI)

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

An implant has the following parts:

    * A microphone, which picks up sound from the environment.

    * A speech processor, which selects and arranges sounds picked up by the microphone.

    * A transmitter and receiver/stimulator, which receive signals from the speech processor and convert them into electric impulses.

    * An electrode array, which is a group of electrodes that collects the impulses from the stimulator and sends them to different regions of the auditory nerve.

An implant does not restore normal hearing.

Instead, it can give a deaf person a useful representation of sounds in the environment and help him or her to understand speech.

Working

In a normal ear, sounds are transmitted through the air, causing the eardrum and then the ossicles (middle ear bones) to vibrate.

This sends a vibratory wave into the cochlea (inner ear).

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 transforming mechanical energy (sound) into electrical energy,

which can then be used to stimulate the cochlear nerve (the nerve for hearing), sending "sound" signals to the brain.

Most cochlear implants operate using several similar components.

Sound is picked up by a microphone worn near the ear.

This sound is then transmitted to a speech processor worn on the body, usually on a belt.

The sound is then analyzed and converted into electrical signals, which are transmitted to a surgically implanted receiver behind the ear.

This receiver then sends the signal through an electrode array (wire) into the inner ear, where the electrical impulses are transmitted to the brain.

Cochlear implant differenct from  hearing aids.

Hearing aids amplify sounds so they may be detected by damaged ears.

Cochlear implants bypass damaged portions of the ear and directly stimulate the auditory nerve.

Signals generated by the implant are sent by way of the auditory nerve to the brain, which recognizes the signals as sound.

Hearing through a cochlear implant is different from normal hearing and takes time to learn or relearn.

However, it allows many people to recognize warning signals, understand other sounds in the environment, and enjoy a conversation in person or by telephone.

Surgery

Surgery for inserting a cochlear implant is performed with the patient fully asleep.

An incision is made behind the ear, sometimes after shaving a portion of the hair behind the ear.

A microscope and bone drill are used to open the bone behind the ear (mastoid bone) to allow the internal part of the implant to be inserted.

The electrode array is then passed into the cochlea (inner ear).

The receiver is placed into a "well" created behind the ear to help keep it in place, and to make sure it is close enough to the skin to allow transmission of electrical information from the external portion of the device.

After surgery, there will be stitches behind the ear, and you may be able to feel the receiver in its "well" behind the ear.

Any shaved hair should grow back.

The external portion of the device will be placed about 3-4 weeks after surgery, to give the incision time to heal.