Cochlear implants are devices that can allow deaf individuals to reintegrate with the hearing world. Unlike hearing aids, which merely amplify sounds, cochlear implants convert received sounds into a series of electrical impulses, which are delivered to the auditory nerve by placement of an electrode array within the scala tympani of the cochlea. An internal receiver-stimulator contains circuitry designed to convert the coded information received from the externally worn speech processor to electrical impulses and governs the activation of specific electrodes. The newest designs for the externally worn components of these devices combine a microphone and the speech processor technology into one unit that is comfortably worn at the ear level. A small connector cable links the ear level unit to a transmitter coil that interfaces with the internal receiver-stimulator and is held in place by a small magnet.
How a Cochlear Implant Works
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Sounds are picked up by the microphone.
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The signal is then "coded" (turned into a special pattern of electrical pulses).
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These pulses are sent to the coil and are then transmitted across the skin to the implant.
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The implant sends a pattern of electrical pulses to the electrodes in the cochlea.
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The auditory nerve picks up these electrical pulses and sends them to the brain. The brain recognizes these signals as sound.
Cochlear Implant (external component) in place
The current technological sophistication of today's cochlear implant systems can restore hearing in adults to a functional level and provide young children with auditory stimulation that benefits them in developing, comprehending and producing spoken communication as well as recognizing and understanding sounds in their environment. These advantages have important implications especially for young children relative to communication acquisition, cognitive development, education, social well being, family relationships, daily life activities and in their future, vocational options.
Candidates for cochlear implantation are evaluated by Aristides Sismanis, MD, Suzanne Hasenstab Ph.D. and the VCU team of audiologists.
After undergoing a two and one-half to three hour operation that involves drilling the mastoid bone behind the ear and placement of the electrode into the inner ear, the patient is usually discharged home the same or next day. In approximately four weeks, programming of the implant is initiated by the cochlear implantation team.
All three commercially available cochlear implants-MedEl, Nucleus 24, Advanced Bionics- are available for implantation at our institution.
An additional consideration is learning to interpret the sounds created by an implant. This process takes time and practice. Speech-language pathologists and audiologists are the professionals frequently involved in this learning process. Not everyone performs at the same level with a cochlear implant. Prior to implantation, all of these factors need to be discussed. Initial programming takes two days with a follow-up visit the next week. The patient is then carefully monitored on a monthly basis for the first 6 months. Bimonthly visits are scheduled up until one year following initial programming. Follow up after the first year of cochlear implant use in 3 to 4 times each year. All follow up programming is provided by the VCUHS Cochlear Implant Team.
Risks of a cochlear implantation
Complications following cochlear implantation surgery are extremely rare at our institution, however, like in any other procedure are potential risks. These may include: bleeding, infection, device malfunction, facial nerve weakness, ringing in the ear, dizziness, and poor hearing result.
One long-term risk of a cochlear implant is meningitis (infection of the fluid around the brain). This is very rare and there have only been 91 cases out of 60,000 patients with cochlear implants. However, 17 of these patients have died. Those patients who had meningitis tended to have several predisposing risk factors including congenital inner ear malformations, previous history of meningitis, immune system dysfunction, age less than 5 years old, and a history of recurrent ear infections. Because the cochlear implant runs between the middle and inner ear, bacteria within the middle ear may spread along the electrode of the implant into the normally sterile inner ear and from there to the brain. Currently, all patients who receive a cochlear implant need to be immunized against the common bacteria that cause meningitis.
Cochlear Implants that have FDA Approval in the USA
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Nucleus (Cochlear Americas )
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Advanced Bionics (Advanced Bionics Corporation)
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Med El (Medical Electronics)
Who is a candidate for cochlear implant
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Adults: Over age 18 years
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Children: Over 12 months of age and older
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Severe to profound, bilateral sensorineural hearing loss (unaided responses)
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No medical or surgical contraindications
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Qualifying scores on specific speech perception tasks (if possible)
(listening tasks for speech sounds, words, sentences)
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Commitment to follow-up
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Support system (family, friends, etc.)
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Participation in educational/rehabilitation services (children)
Who can make referrals?
Anyone (physicians, patients, family members, school personnel.)
What is included in the evaluation process?
Audiological, medical, otological and radiological examinations as well as
patient/family counseling, including, but not limited to:
Hearing evaluations (with and without hearing aids)
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Speech perception testing (listening and understanding speech sounds, words, sentences)
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Developmental evaluation (children only)
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Otological exam (hearing history and health)
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CT or MRI radiographic studies
Some individuals may require:
The Virginia Commonwealth University Medical Center Cochlear Implant Program began in 1986 as one of 24 original programs in the FDA Clinical Trials for multichannel cochlear implants. The program continues as a research study site for all three devices and has been designed as a Center of Excellence . Our cochlear implant team is the veteran implant team in Virginia .
For more information, contact:
VCUHS Cochlear Implant Program
P.O. Box 980150
Richmond , VA 23298-0150
(804) 828-0431 phone (804) 628-0950 FAX
Additional Information on Cochlear Implants on the Web
Cochlear Implants
Cochlear Implants (American Academy of Otolaryngology-Head and Neck Surgery)
Cochlear Implants: Frequently Asked Questions (Bruce Gantz, M.D., Virtual Hospital, University of Iowa)
Sound from Silence: The Development of Cochlear Implants (The National Academies)
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