Cochlear implants are a viable option for those who qualify for the surgery. Unlike a hearing aid that amplifies sound for a person who already can hear, a cochlear implant helps to create the stimulation needed to recognize sound in a person who cannot hear. Its objective is to stimulate the auditory nerves so that a signal is sent directly to the brain. The brain recognizes the signal as sound and allows a person to understand and differentiate the various levels and types of sound in their environment.
"The cochlear implant can take someone who is at the edge of functionality, or someone who is not functioning at all, and bring them back to the point where they can understand speech and have the ability to communicate," says Dr. Herbert Marks, an otolaryngologist at East Jefferson General Hospital who in 1984 performed the first cochlear implant surgery in Louisiana. "It can be a much better option for people who are struggling through life with hearing aids."
The cochlear implant works with three main components: a small device that is surgically implanted in the ear, a microphone and a processor. The implanted device is a transmitter placed under the skin behind the ear and is hooked to thin electrodes wrapped in the cochlea of the ear. The cochlea contains hair-like fibers that when stimulated send the sound signal to the brain. The microphone, an external piece used to collect sound, is placed in the location of the transmitter and held to the head through a magnet between it and the transmitter. Finally, the processor is a small box or, in some cases, a small unit outfitted to be worn similarly to a hear aid.
The three combine to form a pathway of sound to the brain. The microphone picks up sound and sends the information to the processor. The processor, through the use of an internal computer, decodes the sound levels and frequency and sends the signal to the transmitter. The electrodes stimulate the auditory nerve, and the brain then receives the signal.
Although the implant enables the brain to understand sound, the sound is not the same as that for an individual with no hearing problems. It is usually described as more mechanical or even as an AM radio out of frequency.
After receiving a cochlear implant, a patient will consult with their physician to ensure the device is properly functioning, as well as with an audiologist and speech therapist. Since individuals hear or process sounds differently, the audiologist is responsible for coding or "mapping" each patient's processor to individualize the internal computer for optimal sound recognition. The functional ability of the implant is turned on about four weeks after the surgery; it may take months to establish the best level for the patient as they either learn sound for the first time or relearn sound. Regular checkups are also needed to monitor the mapping levels.
"I have had patients literally break down in tears when we turn on the implant for the first time because they may have lived in silence for years or may have never heard sound before," says Dr. Marks. "That is part of the excitement. They can now be engaged in family conversations or (discussions) at work or school. There is no question that it can significantly change their quality of life."
As technology advances, the use of the cochlear implant is increasing. The NIDCD estimates that about 25,000 people in the United States have cochlear implants, but another 250,000 are good candidates for the surgery.