A cochlear implant is a surgically implanted bionic ear for severely deaf individuals who cannot benefit from traditional hearing aids. The cochlear implant directly stimulates the hearing nerves, allowing the patient to perceive sound. A portion of the device is implanted into the inner ear. The battery-operated external portion is worn like a hearing aid.
Who can benefit from cochlear implants?
Cochlear implants do not provide the same quality of sound as conventional hearing aids. They are therefore an option of last resort for the hearing impaired. Generally, patients must meet all of the following criteria to be considered for cochlear implants:
- Permanent sensory hearing loss > 50 dB
- Speech understanding is worse than 50%
- Normal cochlear anatomy
- Normal auditory nerve
- No active infection
What is the appropriate age range for Cochlear Implants?
Children who are born deaf have the best chance of normal language development if they are implanted within the first two years of life. All newborns are screened for hearing loss at birth. Those who fail newborn screening are referred for further testing. If they are confirmed to have profound hearing loss, then cochlear implantation should be considered as early as six months of life.
There is no maximum age for implantation. Adults with progressive hearing loss can benefit from cochlear implants if hearing aids are no longer effective.
What does the surgical procedure include?
Cochlear implantation is typically an out-patient procedure performed under general anesthesia. An incision is made behind the ear, and a hole is drilled into the cochlea, which is the receptor portion of the inner ear. The electrode is threaded into the cochlea, where it lies adjacent to the auditory nerve endings. The skin is closed over the implant. The surgery takes about an hour.
What follow-up care is necessary?
After the surgical site is healed, the audiologist will provide a programmable receiver to convert sound into an electrical signal. The receiver is worn behind the ear, over the implant, and attaches with a magnet. Multiple visits are required to program the receiver for maximal benefit.
What are the risks of the procedure?
The immediate risk is fairly low with an experienced surgeon. However, the implant is likely to destroy any remaining hearing in the implanted ear. This is why we do not perform cochlear implants on patients who still have functional hearing. Because the cochlea has close communication with the cerebrospinal fluid, middle ear infections must be treated immediately to prevent meningitis. Less serious complications include incomplete insertion of the electrode, and failure of the electrode requiring reoperation.
© 2020 Richmond ENT by Michaela Bailey and Mike Armstrong MD. Spanish translation by Michael Reymundi.