What Does Cochlear Implant Surgery Entail?
This is a fairly routine type of surgery for physicians who are trained in ear surgery (Otology, Neurotology, and Skull Base Surgery). It takes about 1.5 hours and involves making an incision behind the ear. The mastoid bone behind the ear is drilled to get to the inner ear and the electrode is placed. The incision is then closed and a dressing applied. Often the patient is kept in the hospital one night for observation, but in other cases the patient can be discharged home the same day as surgery. It is not particularly painful, and patients can resume their normal activities within 2-3 days typically. Because the implant is put into the inner ear, the balance canal function can be altered. Adult patients are often dizzy after surgery for a week or two, although this can last for a longer time period occasionally. The implant is not turned on until the incision has fully healed, about 4 weeks after surgery.
What technologies are used in a cochlear implant?
A cochlear implant is made up of two parts. The external device 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 from 12 to 22 electrodes that stimulate the auditory nerve. These multi-channel implants have the advantage of stimulating many different nerve fibers selectively, 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.
Are there any alternatives to a cochlear implant?
For children, once the diagnosis of severe hearing loss is made, parents may chose to have their child taught in either oral language or a non-oral language such as American Sign Language (ASL). Sign language is a way to teach children how to communicate without having to hear. They can develop close relationships with other people in the deaf community. One disadvantage to this method however, is that it becomes difficult for the child to communicate with people who do not know sign language. Thus, special schooling in schools for the deaf is required.
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.
