Division of Audiology and Speech - Language Pathology

Cochlear Implants

The treatment of deafness has changed radically since the 1950s. Technological improvements have permitted Otologists and Audiologists to offer an increasing array of options for improvement of hearing and adjustments to hearing loss. Leading among these improvements is a treatment called cochlear implantation, which assists persons with severe and profound sensorineural hearing loss to communicate using hearing combined with lipreading.

What are Cochlear Implants?

Cochlear implants are a group of devices that combine electrodes surgically implanted into the cochlea or inner ear with an external sound processor to stimulate the hearing nerve with electrical current.

Since their early introduction in the 1950s, cochlear implants have undergone considerable refinement, and are now a widely accepted form of treatment for persons with little or no usable hearing.

How do Cochlear Implants Work?

While hearing aids amplify sound, cochlear implants work by compensating for damaged or non-functional parts of the inner ear. A number of cochlear implants are currently available, but all consist of four main components:

a microphone, which collects sound from the environment,
a signal processor, which selects and arranges these sounds,
a signal coupler (transmitter and receiver), which converts signals from the processer into electric impulses (in much the same way that normal ears do), and
electrodes, which send the impulses to the brain.

The microphone and processor are worn behind the ear, like a hearing aid. The transmitter may be worn outside the body with a receiver inside, or a connector that protrudes through the skin behind the ear may be used instead. Both types connect the processor to the electrodes.

What to Expect from a Cochlear Implant

Although cochlear implants do not restore or create normal hearing, they can provide a sense of sound, give some auditory understanding of the environment, and help patients to understand speech. Most totally deaf patients who receive a cochlear implant are able to detect medium to loud sounds, including speech at comfortable listening levels. Many patients can learn to recognize some familiar sounds. For many patients, implants aid in communication by improving lip-reading ability. In some, the implant even provides some understanding of words or sentences without the use of lip-reading.

Results vary from person to person, depending on factors such as age at time of deafness, age at implant surgery, duration of deafness, status of the remaining auditory nerve fibers, training, etc.

Who is a candidate for a cochlear implant?

Good candidates for cochlear implants have the following characteristics:

Severe to profound sensorineural hearing loss with very poor speech recognition under headphones
Minimal or no benefit from the use of hearing aids
Medically able to tolerate cochlear implant surgery, which is equivalent in degree of risk to mastoid surgery
Realistic understanding of the risks, benefits and limitations of implantation
For children, failure to develop good oral language skills despite consistent hearing aid use and intensive rehabilitative efforts
A home and educational environment in which oral expression is encouraged and supported

What is involved in the evaluation?

Hearing examinations, with and without hearing aids
Communication evaluation, including tests of speechreading ability and language development [for children]
Dizziness evaluation [for adults], called electronystagmography [ENG]
Test of function of the hearing nerve, i.e. auditory evoked potentials and promontory stimulation or neural response telemetry
Neuropsychological tests as indicated
Radiologic examination
Considerable discussion of the benefits and limitations of cochlear implants

Cochlear Implant Surgery

Cochlear implant surgery is performed under general anesthesia. The surgeon makes an incision behind the ear, opening the mastoid bone to the inner ear. The electrodes (internal portion of the cochlear implant) are placed in the inner ear.

This operation may take from two to five hours, depending on the specific implant being used. Patients may remain in the hospital for one to several days, depending on the device used and the patient’s needs.

One to two months after surgery, the patient returns to the clinic and is fitted with the external portions of the cochlear implant (the processor, microphone, and transmitter). He or she receives instruction in using and maintaining the implant. Regular check-ups and assessments in the following months are also required.

What alternatives are there for Hearing Impaired Persons?

Cochlear implants are not the appropriate choice for all hearing impaired persons, even when their hearing is in the severe to profound category.
Powerful hearing aids, vibrotactile devices, frequency transposing aids, and FM assistive listening devices are among the possibilities that should be explored.
For many people, whether a cochlear implant is appropriate or not, the Implant Team may make recommendations that entail additional training and rehabilitation. Such rehabilitation may include stimulation to maximize use of residual hearing or emphasize visual information, such as speechreading training or learning/supplementing with a sign system.
For persons who cannot undergo implant surgery due to health limitations, such devices as a vibrotactile aid may be recommended.

Does my insurance cover a cochlear implant?

There is a great deal of variability in insurance coverage for cochlear implants. Many forms of insurance have had experience in approving the several phases of cochlear implant evaluation, surgery, and follow-up.
For insurers who are unfamiliar with cochlear implants, the Implant Team can provide direction on obtaining approval, or will make direct contact with the insurer on your behalf.

Contacting the Cochlear Implant Team:

Individuals who wish to inquire about cochlear implants should contact Dr. Jaclyn Spitzer, in writing or by telefax at 212-305-2249 or by relay 212-305-4972. She can also be reached by email at:

jbs50@columbia.edu

For referring physicians: Please contact any of the following Team members: Dr. Lalwani [212-305-1696] or Dr. Spitzer [212-305-4972] for discussion of a possible candidate and/or information about referral procedures. For inquires about implantation in children, please contact Dr. Erik Waldman [212-305-8933] or Dr. Robyn Chapman [212-305-4642]

A Telecommunication Device for the Deaf [TDD] is located at 212-305-0029 and may be used for messages to Team members. In addition, staff in our group are familiar with using the relay operator.


About the Columbia University Center for Deafness

This Center is dedicated to research about the causes, prevention and treatments for hearing loss and deafness.

Current research deals with the rehabilitation of persons with tinnitus [ringing in the ears], function of the auditory hair cells, quality of life in persons undergoing aural rehabilitation and the latest generation of cochlear implants.

The Center is supported by donations, grants, and the Department of Otolaryngology/Head and Neck Surgery of Columbia University.

Additional Resources on Cochlear Implants

Tutorial Article on Cochlear Implants, from IEEE Signal Processing Magazine, September 1998:

Publications and Research by members of the Audiology and Speech Pathology Department

Source: parts of this article were adapted from a brochure published by the American Academy of Otolaryngology – Head and Neck Surgery.

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