Cochlear Implants

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Cochlear Implants

While hearing aids can be helpful for most people with hearing loss, there are some for whom hearing aids either do not help or help insufficiently. In such cases, cochlear implants can be helpful and are being used by more people with severe and profound hearing loss who no longer benefit from hearing aids.

Hearing aids help the majority of people with mild-to-moderate hearing loss, but they can't help everyone. For many people who have severe-to-profound sensorineural hearing loss ("nerve deafness") in both ears, even the most advanced and powerful aids may not adequately help. That's because hearing aids simply amplify sound and this amplified input can sound distorted. Despite being referred to as "nerve deafness," most sensorineural hearing loss is a result of damage to the inner ear (cochlea), not the hearing nerve.

A cochlear implant consists of an internal and external component. The internal component is surgically inserted under the skin behind the ear, and a narrow wire is threaded into the inner ear. The external component, which looks somewhat like a behind-the-ear hearing aid, is connected to the internal one through the skin via an external magnetic disk. 

Incoming sounds are converted to electrical currents and directed to a number of contact points on the internal wire. This operation creates an electrical field which directly stimulates the auditory nerve, thus bypassing the defective inner ear. Unlike hearing aids, cochlear implants convert sound waves to electrical impulses and transmit them to the inner ear, providing people with the ability to hear sounds and potentially better understand speech without reading lips.

The cochlear implant has become widely recognized as an established treatment for profound hearing loss.

Quick Facts on Cochlear Implants

  • Cochlear implants are medical devices that bypass damaged structures in the inner ear and directly stimulate the auditory nerve. They are surgically implanted to improve hearing in people with severe or profound hearing losses. They can create a range of sound, but do not replace normal hearing.
  • Cochlear implants are not indicated for all hard of hearing or deaf people. They are not recommended in people who function well with hearing aids.
  • Cochlear implants can be provided for children as young as 12 months old, as well as adults.
  • More than 188,000 people worldwide have received cochlear implants. (NIDCD, NIH)
  • Cochlear implants can be in one ear or both (binaural)
  • To be considered for a cochlear implant, you will need to receive an evaluation by a physician and audiologist associated with a cochlear implant clinic.
  • Ideal candidates are motivated to work hard in their rehabilitation after surgery. It helps to have good family support and to live close to a clinic in order to conveniently make the follow-up trips for mapping and adjustments.
  • Adjustments (called "mapping") are an integral and essential part of cochlear implant rehabilitation. Mapping is done by trained audiologists who adjust the speech processor to help improve hearing.
  • Cochlear implant performance varies. People hear better over time with practice. It takes a while to get used to hearing sounds in a new way. Speech processors are computers worn as a behind-the-ear device similar in look to a behind-the-ear hearing aid.
  • Use of the phone after implementation varies among individuals. Some people plug into the speech processor directly. Others hold the phone up to the ear, while others are not able to use the phone comfortably after their implant.
  • Waterproof or water resistant devices are now available.
  • The cost of cochlear implants are covered by most insurance plans. Medicare covers cochlear implants. Research shows that they improve the quality of life and are; therefore, cost-effective interventions. If a health care provider tells you that a denial for coverage is received, check to see what appeal options are available. Work with your health care provider or cochlear implant manufacturer for appeal until approved or until all appeal options are exhausted.
  • A variety of assistive devices can be combined with cochlear implants to improve their effectiveness. For example, patch cords can connect speech processors to assistive listening devices. Also a directional hand-held microphone can be used to improve speech pick-up in noisy environments.
  • A hybrid cochlear implant uses two technologies -- a hearing aid which amplifies sound and acoustically transmits the sound through the middle ear to the cochlea as well as cochlear implant technology which converts sound to electrical impulses directly stimulating the hearing nerve in the cochlea.

Manufacturers

Research your options. Many adults and children with severe-to-profound hearing loss may benefit from a cochlear implant. Discuss your options with your hearing health care team. Learn more about the cochlear implant systems. Evaluate information about reliability, performance, and reputation of each cochlear implant manufacturer.

Ask your audiologist and cochlear implant surgeon about the track record of each device manufacturer. Ask questions about warranties and how you will be supported in the future; for example, technology upgrades.

There are three cochlear implant manufacturers who market their products in the United States.

Online Community

Go to our Online Community section to connect with others online.

Ask Yourself the Following Questions

Even with powerful hearing aids, do you:

  • Hear but don't understand?
  • Have to ask people to repeat themselves during one-on-one conversations, even in a quiet room?
  • Need captions displayed to understand TV programs?
  • Avoid social activities because you don' t know what's being said and are afraid you will respond incorrectly?
  • Depend on speechreading to understand a conversation?
  • Find yourself exhausted at the end of the day because communication requires such a high degree of concentration?
  • Have a hard time keeping up at work? Do you find communication at work to be difficult and to interfere with carrying out duties on the job?
  • Have trouble hearing on the phone?
  • Avoid making and answering phone calls?
  • No longer enjoy listening to music?
  • When tested by an audiologist with your hearing aids on, do you score less than 60 percent on your ability to repeat sentences?

If you answered yes to any of these questions, you may be a good candidate for a cochlear implant.

Excerpted from “Successful Aging and Our Hearing”
By John K. Niparko, M.D., and Courtney Carver, Au.D., CCC-A
Hearing Loss Magazine

When a hearing loss is profound (beyond treatable with hearing aids), the hearing loss carries substantial, measurable effects on multiple domains that are important to quality of life (Francis et al, 2001). My colleague, Dr. Howard Francis used a well-tested survey of the things that people consider crucial to the quality of their life. The survey results revealed that impaired communication with others made people vulnerable to low mood and depression, and to some effects on thinking ability. All contributed to a significant reduction in the quality of life experienced by seniors with hearing loss.

For those with more advanced, severe-to-profound sensorineural hearing loss, the cochlear implant provides a physiologically useful code of electrical signals. These signals trigger trains of impulses in nerves within the ear in severe-to-profound deafness. The "cochlear implant" is actually a system of technology. A portion of that system worn on the ear processes information from incoming sound. The processed information is transferred across the skin to an implanted receiver-stimulator, which serves as a control tower that receives coded signals and transfers that code directly to the nerve of hearing.

A cochlear implant is designed for those who do not benefit from powerful hearing aids in a material way (a level of understanding of at least half of the words of every day communications). A large number of clinical studies now document the benefits of the cochlear implant in providing speech and environmental sound recognition.

The critical question for many seniors contemplating a cochlear implant is how to predict what level of benefit might result. A number of studies have applied multivariate statistical testing (assessing the many factors that can influence hearing results) in an effort to analyze cochlear implant results in seniors 65 years of age and older. Studies over the past 20 years document better speech-recognition performance in elderly listeners in a quiet environment with the use of a cochlear implant.

As results from these studies accumulate, two factors have emerged as carrying significant power in explaining how much speech recognition will improve with a CI. Duration of deafness and the word understanding scores achieved in testing before an implant is placed are the main factors that carry significant predictive power in forecasting the benefit of a cochlear implant. A shorter duration of deafness and higher levels of retained speech understanding (for example in the 20 to 50 percent range) predict greater gains in speech understanding. About one-fourth of the overall range of outcome can be explained based on the length of deafness and about one-sixth of depends on the word understanding capabilities prior to implantation. Other patient, ear and device variables demonstrated no significant correlations with the benefit achieved with respect to speech recognition.

A more recent analysis of a large group of patients indicates that age carries a very small effect in determining post-operative outcome and offers encouragement for seniors with advanced levels of hearing loss (Leung et al, 2005). Instead, studies continue to bear out that a more significant factor is the ratio of duration of deafness to age at implantation (Tyler & Summerfield, 1996)

Because duration of deafness and pre-implant speech recognition most consistently predict outcome, a concept of an “auditory foundation” is suggested. An “auditory foundation” appears to reflect the ongoing low-level activity that allows nerves within the hearing pathway to retain their potential to work well (in contrast to completely abolished activity that silences the pathway). The auditory foundation:

  • may be considered a form of cognition that reflects an internalized memory of the sounds of speech and the ability to process sensory inputs that are based in sound.
  • appears key in predicting the ability to use restored hearing from a cochlear implant to discriminate words, and
  • may moderate effects that might occur with senescent changes in elderly implant recipients.

These observations are further underscored by assessments of ultimate outcome. Implant recipients report significant satisfaction expressed as improvements in quality of life after receiving a cochlear implant. While some reports indicate that elderly people achieve the same or nearly the same level of benefit in speech-recognition as do younger recipients, elderly cochlear implant users may have a slower learning curve.

For people over the age of 70, the cochlear implant may produce, on average, slightly lower speech-recognition scores than younger people. These differences may reflect some limits in processing information that is presented at a rapid rate by the cochlear implant. Fortunately, however, these effects appear to be small.