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Cochlear implant

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Description

A cochlear implant (such as the House 3M Cochlear Implant is an electronic device implanted surgically to help a person hear by bypassing the poorly- or non-functional portions of the normal hearing pathway by sending signals directly to the auditory nerve. There are generally 4 parts: a microphone, Speech processor, transmitter, and electrode array. The microphone is outside the body (generally behind the ear) and detects sounds. The speech processor filters the input from the microphone, and the transmitter converts this into an electronic signal. Finally, the electrode array sends these electric signals to specific areas of the auditory nerve, which causes the person to “hear” a sound.
A cochlear implant, courtesy http://www.dizziness-and-balance.com
A cochlear implant, courtesy http://www.dizziness-and-balance.com
These sounds are not like the person could hear if they were not hearing impaired; they are filtered and coded by the implant, and the person can learn to discern these sensations, but they do not actually hear the outside sounds. People can learn to understand the signals well enough to have a conversation by phone, as well as recognize environmental sounds.

Patient Population

People who are completely deaf or severely hard of hearing are candidates for this type of device. There are 188, 000 people with cochlear implants (http://www.nidcd.nih.gov/health/hearing/coch.asp); 41,500 adults and 25,500 children in the US are among these. In adults, patients can associate the new auditory sensations with sounds they remember from while their hearing was intact, and in children(usually 2-6 years old), cochlear implants can be used in conjunction with intensive therapy to help them learn to speak. The FDA has determined that a child must be 12 months old to have the device implanted.

Benefits/Risks

Benefits and risks of implanting this device abound. Adults often regain hearing immediately, and can improve over time. Recipients can perceive the level of intensity of sounds, understand speech without visual cues (such as lip reading), and can still sometimes enjoy music. For these benefits, however, there are many potential drawbacks. Patients undergoing the procedure have the usual risks of general anesthesia, which is relatively low (see them here: http://www.webmd.com/pain-management/tc/anesthesia-risks-and-complications), but have other, more severe risks to consider.
The procedure may harm the facial nerve, which lies close to the location of the implant, and may cause permanent or transient weakening or paralysis of the facial muscles on the side of the implant. Patients also have the risk of contracting meningitis, leaking cerebrospinal fluid or perilymph fluid from the inner ear, tinnitus, altered taste sensations, numbness around the ear, vertigo, or an infection of the wound from the incision. They may also lose what residual hearing they have left, and may not have any of the hearing benefits that the implant usually provides. For a full list of potential risks and benefits, go to http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/CochlearImplants/ucm062843.htm

Further information

The National institute on Deafness and Other Communication Disorders has a list of organizations relevant to the deaf and hard of hearing at http://www.nidcd.nih.gov/directory/keyword.asp?keyword=22

Sources