| Cochlear Implants What is a cochlear implant?
The sound waves then are carried through the middle ear by the middle ear bones (the ossicles). The sound pressure waves are then converted to nerve signals within the inner ear (the cochlea). A cochlear implant bypasses the normal sound conduction mechanism through the external, middle, and inner ear, and directly stimulates the auditory nerve. An implant does not restore or create normal hearing. Instead, under the appropriate conditions, it can give a deaf person a useful auditory understanding of the environment and help him or her to understand speech. Cochlear implants were approved by the Food and Drug Administration (FDA) in the mid-1980s and are covered by insurance policies, Medicare, Medicaid, and Vocational Rehabilitation. There are now more than 60,000 patients worldwide who have received cochlear implants. Who is a candidate for a cochlear implant? What technologies are used in a cochlear implant?
consists of a microphone behind the ear that hears the sounds in the environment. These sounds are then digitized and processed by a small computer called a speech processor. Small speech processing units can be hidden behind the ear while larger ones have to be worn on your belt. Of course, the bigger the processor, the more capability it has to select speech signals out of the environment, ultimately improving hearing. However, computer technology is continuing to improve so that behind-the-ear speech processors now provide quite good results. The signals from the speech processor are sent to the implanted part of the device though the skin using a magnet. The implanted part is an electronic device that is put under the skin behind the ear.
An electrode connected to the device is inserted into the inner ear.
The electrode is simply a bundle of tiny wires that have open contacts spread out along the length of the cochlea. Thus, the electrical signals can be sent to different areas of the cochlea and represent different frequency sounds. State-of-the art cochlear implant devices now have up to 24 electrodes that stimulate the auditory nerve. These multi-channel implants have the advantage of stimulating many different nerve fibers individually, thereby transmitting more detailed information to the brain. The more information that reaches the brain, the greater the patient's ability to understand what is happening in his/her environment. What are the benefits of a cochlear implant? Are there any alternatives to a cochlear implant? In contrast, if oral language training is selected, hearing aids will be fitted to amplify speech and environmental sounds to help the child learn to communicate. If hearing aids do not provide sufficient benefit for oral language development, a cochlear implant will be recommended. Cochlear implants have also benefited school age and older children as well to help them develop and improve their communication skills and achieve their educational goals. Most children who receive a cochlear implant end up being mainstreamed in community schools and do quite well with their peers. For adults, the decision to proceed with a cochlear implant is personal, just like that to get a hearing aid. Interestingly, many patients don’t treat their senses equally. Although not a perfect analogy, hearing can be compared to vision. If you began having progressive loss of vision, you would immediately get your eyes checked and get glasses. If surgery was needed to preserve your vision, most would have the surgery. What does cochlear implant surgery entail? What are the risks of a cochlear implant? 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, less than 5 years of age, and a history of recurrent ear infections. Because the cochlear implant runs between the middle and inner ear, bacteria within the middle ear may tract along the implant into the normally sterile inner ear. The inner ear has connections with the brain, through which the infection may spread. Currently, all patients who receive a cochlear implant need to be immunized against the common bacteria that cause meningitis. 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. What research projects are on-going at Baylor regarding cochlear implantation? One particularly exciting area of research that has not yet reached the clinical stage yet, is the development of alternative techniques to restore hearing in patients with high-frequency hearing loss. More information on this is available here. The cochlear implant team: Neurotology: Cochlear Implant Coordinator: For inquiries or more information, please contact: Basic science research related to hearing preservation and restoration can be found here. Cochlear Mechanics and Hearing Loss Laboratory Home Page | Department Home Page | BCM Public | BCM Intranet | Privacy Notices | Contact BCM | BCM Site Map | ©2001-2007 Baylor College of Medicine
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