What are Cochlear Implants?
A cochlear implant is a small electronic device that helps provide the sense of sound to a person who is severely hard of hearing or profoundly deaf. The device does not restore hearing but provides a useful representation of sound that allows the hearing-impaired person to understand speech and sounds in their environment.
What are the parts of a Cochlear Implant?
A cochlear implant is comprised of external parts that can be placed behind the ear and internal parts which are surgically implanted underneath the skin. The parts of the cochlear implant are:
- A microphone which picks up sounds from the surrounding environment
- A speech processor that processes the sounds into signals for the auditory system
- A transmitter and a receiver which converts signals from the speech processor into electrical impulses
- An electrode array which collects the electrical impulses and sends them to the various parts of the auditory nerve
How do Cochlear Implants work?
Cochlear implants bypass the damaged portion of the ear to directly stimulate the auditory nerve unlike hearing aids which amplify sounds so they can be picked up by the damaged portion of the ear. The electrical impulses generated by the cochlear implant stimulate the auditory nerve, which perceives these impulses as sound. Hearing through a cochlear implant is quite different from normal hearing and it requires time to learn.
Benefits of Cochlear Implants
Cochlear implants allow people who are severely hearing impaired to:
- Understand speech when speaking to someone directly or over the phone
- Recognize sounds in the environment
- Be alerted of warning sounds
Ideal Candidates for Cochlear Implants
You may be a candidate for a cochlear implant if you:
- Experience hearing loss despite wearing your hearing aids
- Have very limited hearing with poor quality in both ears
- Are unable to understand half the words spoken to you when wearing your hearing aids
- Rely on lip-reading despite wearing your hearing aids
Preparing for Cochlear Implant Surgery
Specific instructions will be provided by your surgeon. In general, you should:
- Stop smoking as it can slow down the healing process.
- Inform your surgeon about any health conditions, allergies, and regular medications.
- Avoid eating 8-12 hours prior to the surgery.
How is a Cochlear Implant placed?
- The surgery is performed under general anaesthesia.
- A small incision is made behind the ear and the mastoid bone is opened.
- The facial nerves are identified, and an opening is created between them to access the cochlea, which is a hollow spiral bone located in the inner ear.
- The implant electrodes are inserted within the cochlea.
- The implanted receiver is placed underneath the skin behind the ear and secured to the skull.
- The incision is then closed with sutures, and you are transferred to the recovery room for observation for about 1-2 hours.
Recovery after Cochlear Implant Surgery
You will be given specific instructions on how to change surgical dressings and care for the incision area. A follow-up visit is usually required after 1 week. After complete healing, which may take about 1 month, the external components of the cochlear implant will be fitted which include the speech processor and the microphone. A period of therapy and training is necessary after the surgery to learn how to optimally use the cochlear implant.
Risks of Cochlear Implant Surgery
Cochlear implant surgery is a very safe procedure; however, as with any surgery there are minimal risks involved that include:
- Infection
- Bleeding
- Swelling
- Ringing sensation in the ears
- Damage to the facial nerve
- Risks of anaesthesia
Prognosis after Cochlear Implantation
Early intervention is the key to successful cochlear implantation as the opportunity for improvement tends to decrease as the hearing loss worsens. Research shows that adults who lose their hearing late in life can learn to associate signals from the cochlear implant with sounds they remember from the past including speech, and eligible children who obtain a cochlear implant before the age of 18 months can develop language skills at a comparable rate to children with normal hearing.