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Cochlear implant
Surgery is performed while the patient is under general anesthesia and takes approximately two to three hours. The surgeon makes an incision behind the ear and forms a slight depression in the mastoid bone, where the internal device rests. The surgeon then creates a small hole in the cochlea and threads the electrode array of the internal device through this hole. The incision is closed so that the internal device is beneath the skin. Most patients feel well enough to return home the day of surgery.
Two to six weeks after surgery, after the incision has healed, the external components of the device can be programmed and activated. There is no hearing ability from the implant until this is done.
The activation includes:
Attaching the headset.
Fitting the headset
After the incision has healed and swelling has subsided, an audiologist attaches a headset. The headset contains an external magnet that is aligned with a magnet implanted inside the head during surgery. Adequate magnetic attraction is necessary to hold the headset over the internal receiver/stimulator so that information can be transmitted across the skin via radio frequency.
Cochlear implant check
The device is checked through a computer system, by communicating information between the cochlear implant and the external speech processor. Every component, including each electrode, is checked to make sure it is working properly.
Checking the cochlear implant.
Programming the speech processor
The speech processor is programmed with a special computer system by an audiologist. Each electrode is fine-tuned for threshold (first hearing) and for comfortable listening levels. As each electrode is turned on, very small increases of electrical current are delivered to the hearing nerve until the patient hears a soft beep or tone. Once the softest hearing level is set, the patient listens for an increase in loudness until these beeps or tones become comfortable to hear. These steps are repeated until all electrodes are set for soft and comfortable levels. From these loudness judgments, a "hearing map" is created. The map is a specially designed set of instructions that tells each electrode how to stimulate the nerve endings in the cochlea.
Once a map is created and downloaded into the speech processor, the speech processor is turned on, and the patient hears through the cochlear implant for the first time. On this first day, speech usually sounds garbled or high-pitched. Environmental sounds may be difficult to identify. Over time, speech and environmental sounds become clearer and more natural. The audiologist will verify that the cochlear-implant recipient is able to tolerate a range of sounds, such as conversational speech, loud speech, hand clapping, coughing or doors shutting.
Learning how to use the external equipment
The cochlear implant recipient is shown how to wear and operate the speech processor and its accessories. Care and maintenance of the device and its accessories are also reviewed.
Several programming sessions are required to obtain and maintain optimal performance from the device. Patients return the day after activation for a recheck — and again after two weeks, one month, three months, six months, nine months and one year. After the first year, patients usually schedule annual appointments.
Rehabilitation involves training the brain to understand sounds heard through the cochlear implant. Since the cochlear implant restores awareness for all sounds, patients sometimes are overwhelmed initially. Speech and everyday environmental noises sound different from what they remember; it takes time for the brain to recognize what these sounds mean. This process is ongoing and is best achieved by wearing the speech processor continuously during waking hours.
Patients are given listening exercises to do at home. The difficulty level of these exercises varies. For some patients, weekly aural rehabilitation therapy may be necessary to help retrain the brain to hear. Speech therapy may be recommended for cochlear implant patients whose speech has been significantly affected by hearing loss.
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