Cochlear Implant

What is a cochlear implant?

· Small, complex electronic device that can help to provide a sense of sound to a person who is profoundly deaf or severely hard-of-hearing.
· The implant procedure involves surgery to insert the device under the skin behind the ear. Electrodes are attached, providing a direct pathway to the cochlea within the inner ear.
· When the implant detects sound, impulses are sent through the auditory nerve to the brain, creating an effect similar to hearing.
· A cochlear implant is a device that provides sound perception through direct electrical stimulation of the hearing nerve, bypassing the inner.
· The implant consists of :
o An external portion that sits behind the ear :
§ sound processor
§ a cable
§ a microphone
o An internal portion that is surgically placed under the skin and has the following parts :
§ A microphone : which picks up sound from the environment.
§ A speech processor : selects and arranges sounds picked up by the microphone.
§ A transmitter and receiver/stimulator : 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.But it can give a deaf person a useful representation of sounds in the environment and help him or her to understand speech.
· While the implant does not completely restore hearing, most recipients find that they are able to receive significant auditory clues, enabling them to speak and understand oral communication.

How does a cochlear implant work?

· Hearing aids amplify sounds so they may be detected by damaged ears.
· Unlike a hearing aid that simply amplifies sound, a cochlear implant actually converts sound into electrical impulses that the brain can interpret.

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

The primary benefits of a cochlear implant are:

Aid in lip reading
Perception of environment sounds
Aid in monitoring the volume of one's own voice.

Risks :
· Usually with surgery - Bleeding, infection, problems with anesthesia or healing, dizziness, or injury to the facial nerve.
· Mechanical or electrical failure, rejection, infection and problems what would require removal or replacement of the implant.

Who gets cochlear implants?

· Deaf or severely hard-of-hearing can be fitted for cochlear implants.
· Adults who have lost all or most of their hearing later in life often can benefit from cochlear implants.
· The cochlear implant is designed for patients with sensorineural hearing loss that have failed conventional treatment including medications and hearing aids.
· Sensorineural - abnormality of the inner ear or auditory nerve that prevents transfer of electrical signals to the auditory nucleus

Cochlear implant

· Surgical procedure and therapy to learn or relearn the sense of hearing.
· Cochlear implantation surgery is performed under general anesthesia
· Takes approximately one to two hours.
· An incision is made behind the ear and operating with the aid of a microscope, the surgeon drills away a portion of the mastoid bone (hard bone behind the ear) to gain access to the inner ear.
· A small opening is created into the cochlear.
· The electrode array is threaded into the cochlea and its outer end is attached to the bone of the skull.
· The receiver/stimulator is secured to the skull, and the incision is closed with stitches.
· The patient returns at approximately one month following surgery to begin using the sound processor.

References
http://www.nidcd.nih.gov/health/hearing/coch.asp
http://www.ciafonline.org/theimplant.html
http://www.umm.edu/otolaryngology/cochlear.htm
http://www.med.umich.edu/oto/ci/implant.htm