Cochlear implant surgery involves the placement of an electronic hearing device, called a cochlear implant, to help severely deaf people hear speech and environmental sounds. The device is implanted into the cochlea, the part of the inner ear responsible for auditory perception. It is activated several weeks after surgery to allow the wound to heal. As with any surgical procedure, cochlear implant surgery does pose risks and concerns for some patients, and some benefit from the implant more than others.
Before the procedure begins, an ear surgeon shaves a small portion of hair around the ear where the device will be implanted. The patient is then placed under general anesthesia, and the surgeon drills a small hole in the mastoid bone on the side of the skull to access the inner ear. Electrodes are attached to the cochlea inside the ear, the receiver is attached to the outside of the skull just behind the ear, and the wound is stitched closed. Patients usually go home several hours after surgery and can return to work or school within a week.
After the surgery, the stitches around the device dissolve on their own within a few weeks. Patients must keep the area dry and clean for several weeks to lower the risk of infection and device malfunction from an incision that does not heal properly. Injury to facial nerves during the procedure is possible, and some patients' bodies reject the implants. Any hearing present at the time of surgery is usually lost following the procedure until the cochlear implant is activated.
Cochlear implants are usually activated and programmed within four weeks after cochlear implant surgery, once the wound is fully healed. The wait is usually longer for children than for adults. Once the device is activated, patients must undergo auditory and speech therapy to help them adjust to the new sounds transmitted to the inner ear through the device.
The external portion of the implant contains a microphone and transmitter to pick up and transmit sounds through electrical currents to the inner ear, which sends a signal to the brain that the patient learns to recognize as speech or other sounds. Many cochlear implant patients describe the sound as mechanical. This can make it difficult for implant patients to carry on telephone conversations or listen to music, though many are able to process these sounds well.
Patients who have been deaf for many years often take longer to adjust to the implant and may not benefit from cochlear implant surgery as much as someone who has only been deaf for a short time or a deaf child who receives an implant early in life. Patients who work extensively with speech-language pathologists and audiologists often have the best results from the surgery. The process of learning to process sounds and form speech similar to a hearing person can take months or years.