What is a cochlear implant?
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A cochlear implant is a device that may restore some hearing for people with substantial sensorineural hearing loss. This is a type of hearing loss caused by problems in the inner ear. During surgery, the device is implanted or placed in the inner ear. Research indicates that cochlear implantation gives patients with severe to profound hearing loss access to sounds and speech (Firszt, et al., 2004; Geers, Nicholas, & Seedy, 2004). Also, the method has been found to improve quality of life. (Hawthorne et al., 2004).
A cochlear implant is made up of internal and external parts. The receiver/stimulator is implanted in the temporal bone behind the ear, and the electrode array is placed in the cochlea of the inner ear. The device also includes the speech/sound processor, which is worn behind the ear. The sound processor converts speech and sounds into electrical energy. The implant directly stimulates the hearing nerve.
How can you find out if you or your child is a candidate for cochlear implants?
The process calls for many appointments and thorough testing by different types of specialists. You may be required to take any or all of the following steps:
- Comprehensive audiologic diagnostic testing—These tests assess hearing loss and help to choose the best follow-up services and/or technology.
- Audiological cochlear implant evaluation—Your current hearing aids will be checked to see how well they work and how well they allow you to function.
- MRI and/or CT scan—These tests show the internal structures of the inner ear.
- Medical and surgical consultations: The surgeon will meet with you before surgery to discuss instruction, the procedure, and what to expect after surgery in terms of healing and possible hearing outcomes.
- Communication evaluation: Auditory, speech, and language skills and are evaluated.
- Balance assessment: Testing is done to evaluate the vestibular (balance) system. The system is closely linked to the structures involved in hearing.
- Psychology consultation: Goals, motivation, and family support are evaluated. Outcomes are discussed
- Insurance consultation: Individual coverage is considered. The financial impact of the procedure is discussed.
- Implant consultations: This series of meetings relates to choosing and becoming comfortable with the device. The meetings also review device programming, troubleshooting, and keeping track of progress.
In general, cochlear implants are appropriate for:
- adults with bilateral (both ears) moderate-to-profound sensorineural hearing loss
- children ages 2 to 18 years with bilateral severe-to-profound sensorineural hearing loss
- children younger than age 2 years with bilateral profound sensorineural hearing loss
Cochlear implants may be suggested when hearing aids no longer allow the wearer to understand speech well. Audiologic assessment includes testing both with and without hearing aids. This will show the degree of benefit that a patient’s hearing aids are currently providing. There must be no medical or radiological contraindications. Other factors include motivation to participate fully in the (re)habilitation process, family support, and a clear understanding of the limitations of cochlear implants.
What are the outcomes and benefits of cochlear implantation?
Both adults and children can benefit from cochlear implants. The age of patients who have received these implants ranges from 8 months to over 90 years. However, cochlear implants do not restore normal hearing function. Performance varies based on a multitude of factors, including:
- Duration of hearing loss
- Consistent use of amplification prior to cochlear implantation
- Cause of hearing loss
- Age of hearing loss onset
Success with a cochlear implant cannot be predicted. However, the following factors tend to suggest the likelihood of a good outcome:
- Pre-implantation hearing system status
- Exposure to sound (and especially speech) before loss of hearing
- Shorter duration of hearing loss
- Consistent use of amplification prior to implantation
- High number of functioning hearing nerve fibers
- Lack of anatomical complications
- Consistent use of the cochlear implant
- Daily use during all waking hours
- Attending scheduled appointments
- Participating in auditory therapy
- Consistently developing and implementing strategies for listening and speaking (pediatrics)
- Educational placement that emphasizes auditory skill and spoken language development
- Realistic goals and sincere desire to be part of the (re)habilitation process
How is a cochlear implant different from a hearing aid?
A cochlear implant is very different from a hearing aid and is appropriate for individuals for whom hearing aids fail to provide benefit. A hearing aid makes sounds louder. Sound still travels through all the portions of the ear (outer ear, middle ear, inner ear) to the hearing nerve. A cochlear implant bypasses these structures and directly stimulates the hearing nerve with electrical energy. Because hearing aids amplify sounds and rely on the hearing system to convey the message, people with severe to profound hearing loss may be able to hear, but not understand speech well. The main objective of a cochlear implant is to improve speech understanding in quiet. Clarity with a cochlear implant is usually better than a hearing aid because the implant does not make sounds louder but delivers them to the hearing nerve.
What can I expect with a cochlear implant?
Nearly all people who get cochlear implants can detect sound, including speech, at comfortable levels. Most people can pick out everyday sounds such as car horns, doorbells, and birds singing. The majority of people with implants develop the ability to recognize and understand speech in quiet environments without visual cues. Some can use the telephone, appreciate music, and converse successfully. The best results are seen in patients who have had some language skills or who receive a cochlear implant shortly after losing their hearing. Some listening environments, such as those involving background noise or those without visual cues, such as talking on the telephone, are particularly hard. Auditory therapy and cochlear implant reprogramming may improve performance. However, success in these challenging environments varies greatly among recipients.
The cochlear implant surgical procedure often can be performed as an outpatient surgery. In the time after surgery, an expert rehabilitation team works closely with each patient. Follow-up appointments will test sound detection and speech perception in quiet and in noise. This will allow the team to find out how well the implant is working and to create programming tips. Learning how to use new sound information requires time, experience, and practice.
- National Institute on Deafness and Other Communication Disorders. Health Info: Hearing, Ear Infections, and Deafness: Cochlear Implants. www.nidcd.nih.gov Accessed 6/24/2011
- Wilson, B, Dorman MF. Cochlear Implants: A remarkable past and a brilliant future. Hearing Research Aug. 2008. Vol. 242, Issues 1-2, p. 3-21.
- American Speech-Language-Hearing Association. Information for the Public: Hearing and Balance: Cochlear Implants www.asha.org Accessed 6/24/2011
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