Cochlear implant (CI) surgery is a procedure to implant a device that can help individuals with severe hearing loss or deafness. It’s not a hearing aid; it inserts electronic signals representing sound directly into the cochlea. This Tech Focus will introduce the surgery, recovery, activation, and rehabilitation.
1. Before the Surgery: You will be asked to choose one of the three cochlear implant brands, and several compatible accessories, including batteries, remote microphones, TV transmitters, and other options. Each brand has different internal devices, and accessories that are not compatible with other brands. There are two basic styles of external processors to choose from: a behind the ear model that has a separate coil that attaches by a magnet to the internal device and an off the ear model. Different clinics may provide patients with one or two processors for each implanted side. If you qualify and if your surgeon agrees, it may be possible to implant both ears in a single surgery, but the most common procedure is one side at a time.
2. Anesthesia: You'll be given general anesthesia, so you'll be unconscious during the procedure and won't feel any pain.
3. Incision: A small incision is made behind the ear. Surgeries done a few years ago used to require an incision of several inches, but most surgeons now use a very small incision right behind the ear and don’t require much or any hair to be shaved. The skin behind the ear is gently lifted and the surgeon will create a shallow area under the skin on the outside of the mastoid bone, where the internal part of the implant is placed. A thin channel in the mastoid bone will be carved into the outside of the mastoid bone leading to the cochlea.
4. Placement of the Implanted Part: The surgeon will carefully place the internal part in the shallowed out of the mastoid bone just under the skin behind the ear, and then insert the implant electrodes into the cochlea, which is a snail-shaped structure in the inner ear responsible for hearing. The internal part looks like figure 1. It’s very thin and has two wires: the short wire is a ground wire and a longer electrode array that’s curled at the end to conform to the shape of the cochlea upon insertion. The small circle is a little magnet that your external processor will use to transmit the signals representing sounds through your skin to the internal part. The electrodes can electrically stimulate nerve cells in the cochlea, which will then cause nerve signals representing sound to be sent up the auditory nerve to the brain for processing. It’s the brain that perceives the sound.
5. Closing the Incision: The incisions are usually closed with sutures, and the surgery site is typically covered with a bandage.
6. Recovery: The surgery is usually done in a hospital, but most people can go home the same day. After the surgery, you'll need some time to recover and may experience mild discomfort or swelling. You should arrange for someone to drive you home, and plan to take it easy for a few days. You'll be given instructions for post-operative care and pain medicines, in case you need them, but many can manage pain with just acetaminophen. Typically, you’ll just let the bandage come off on its own, and the sutures will either disappear or the surgeon will remove them. There’s usually a short time that you should wait before getting the incision wet, and some limits on how much weight you can lift during recovery.
7. Activation: About 2-6 weeks after surgery, the external speech processor is fitted by your audiologist, and the device is activated, and each electrode is “mapped” to provide the right amount of stimulation to nearby nerve cells for any volume of sound. This is the first time you may hear sound from the cochlear implant.
8. Rehabilitation: Rehabilitation and auditory training are essential to adapt to the new way of hearing with the cochlear implant. Your brain will need time to learn or relearn how to perceive the sounds it hasn’t heard for a while (or ever). You may initially just hear “bells and whistles”, robotic speech, or chipmunk-like sounds, but it will get better as your brain figures it out. Music may take longer. No one can predict how long it will take for your brain to make things sound more like they should. It may never be perfect, but your hearing is very likely to be amazingly better than it was when you qualified.
