Definition

A cochlear implant is a surgically-implanted electronic device that helps provide sound to a person with severe sensorineural hearing loss. This is hearing loss usually caused by damage or a defect in the inner ear. Cochlear implants bypass damaged hair cells in the inner ear and directly stimulate the auditory nerve to send information to the brain.

Cochlear implants have three parts:

• Speech processor—The speech processor looks like a long, narrow calculator. It is worn behind the ear or on a belt. It amplifies sound, converts it into digital signals, and sends these signals to the transmitter.
• Transmitter—The transmitter is a headphone that is worn behind the ear. It receives electrical signals from the speech processor and transmits them through the skin to the receiver.
• Receiver—The receiver is the part that is implanted. It is a magnetic disk about the size of a quarter. It is placed under the skin behind one ear. A wire that leads from the receiver to an electrode is placed in the inner ear where it stimulates the acoustic nerve.

Parts of the Body Involved

The cochlear implants is placed in the ear.

	The Cochlea
	© 2008 Nucleus Medical Art, Inc.

Reasons for Procedure

Cochlear implants provide a heightened sense of sound for adults and children with profound hearing loss. They are designed for people whose hearing does not improve with surgical correction or the use of a hearing aid. Cochlear implants will not restore or create normal hearing.

Risk Factors for Complications During the Procedure

• Previous surgery
• Previous chronic ear infections
• Congenital anomalies
• Ossification of the cochlea

What to Expect

Prior to Procedure

Your doctor will likely do some or all of the following:

• Ear (otologic) evaluation—The external and middle ear are examined to check for infection or abnormalities.
• Hearing (audiologic) evaluation —An extensive hearing test that measures how well you hear without a hearing aid.
• MRI or CT scan —These tests are taken to evaluate the anatomy of your inner ear.
• Physical exam—This includes a medical history and physical exam to ensure that general anesthesia is safe.
• Psychological evaluation—This may be recommended to determine how well you are likely to cope with a cochlear implant.

During Procedure

Anesthesia will be administered.

Anesthesia

General anesthesia is used for this procedure.

Description of the Procedure

There are two parts to the procedure:

• Implantation of receiver—An incision is made behind the ear to open the mastoid bone leading to the middle ear. The receiver is implanted and attached to several tiny electrode bands.
• External hook-up—After 4 to 6 weeks, the area should be healed. At this point, the transmitter headpiece and speech processor are hooked up.

After Procedure

Healing takes 4 to 6 weeks. You will not be able to hear through the device during this time. Once you have healed, you will have a "hook-up" session, in which the external parts of the device are fitted.

Over the next few months, as hearing improves, your doctor will continue to make adjustments to the speech processor. This is called "mapping."

How Long Will It Take?

The implantation procedure usually takes about 1½ to 2 hours for adults, and up to 5 hours for children.

Will It Hurt?

Anesthesia prevents pain during the procedure. Pain is moderate after the procedure.

Possible Complications

• Postsurgical infection at the site of implantation
• Damage to a facial nerve
• Permanent damage to balance organs in the ear (rare)
• Emotional distress due to higher expectations than the technology can achieve
• Poor quality of hearing following the surgery

Average Hospital Stay

This is determined on an individual basis.

Postoperative Care

You will have frequent follow-up visits for the following:

• Headpiece fitting, done 4 to 6 weeks after surgery
• Adjustments to the speech processor (mapping)
• Ongoing evaluation of hearing status

In addition, you'll have cochlear implant training. This will help improve your ability to:

• Identify sounds
• Read lips
• Develop speech skills

Outcome

A cochlear implant should improve the ability to sense sound. Most people with cochlear implants can hear medium to loud sounds and recognize speech at normal decibel levels. Results will vary, depending on the age of initial deafness, degree of hearing impairment, condition of the nerve fibers, and general health.

Call Your Doctor If Any of the Following Occurs

• Pain
• Dizziness or vomiting
• Facial paralysis
• Signs of infection, including fever and chills
• Redness, swelling, increasing pain, excessive bleeding, or discharge at the incision site
• Cough, shortness or breath, chest pain, or severe nausea or vomiting

RESOURCES:

American Academy of Audiology
http://www.audiology.org

National Institute on Deafness and Other Communication Disorders
www.nidcd.nih.gov/health/hearing/coch

CANADIAN RESOURCES:

Cochlear Implant Awareness Foundation
http://www.ciafonline.org/index.html

Hospital for Sick Children
http://www.sickkids.ca/cochlearimplant/

References

Cochlear Implant Association, Inc. website. Available at: http://www.cici.org/ .

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