Cochlear Implant
Cochlear implant is an electronic device to help babies having severe or profound loss, or total deafness to hear sounds. It is very different from hearing aids, and unlike hearing aids, does not make sounds louder. It neither restores normal hearing nor is a cure for hearing loss.
How does a Cochlear Implant work?
A cochlear implant consists of two main parts:
i.External Processor with microphone and transmitter – sits outside on head behind the ear
ii.Receiver and Electrode array – inserted surgically under the skin close to the ear with an attached electrode connecting the receiver to the cochlear (auditory) nerve.
The microphone picks up sounds from the environment which is then passed to the speech processor. Sounds from the speech processor are sent to the transmitter and then to the receiver. The receiver converts the sounds to electric signals.
The electrode array picks up the electric signals from the receiver and transmits them directly to the auditory nerve.
These signals are sent to the brain where they are interpreted as sound.
Thus, a cochlear implant bypasses the outer-middle-inner ear since it directly stimulates the auditory nerve.
Image Source: Wikimedia Commons. Medical gallery of Blausen Medical 2014.
INTENSIVE TRAINING AFTER COCHLEAR IMPLANT SURGERY – A VERY IMPORTANT STEP TO MAKE THE MOST EFFECTIVE USE OF THE COCHLEAR IMPLANTS!
After recovery from surgery, the processor is activated. The implant is then mapped to the actual hearing thresholds of the baby, a process which may take 1-2 months. Babies start to perceive sounds, and training is given to develop listening, speech and language. It is done by a speech language pathologist (SLP) or an auditory verbal therapist. This training happens in 3-4 sessions of 1 hour each week for one year. Sometimes mapping may be required periodically.
However, the baby benefits enormously if the child is enrolled in an Early Intervention-cum-pre-school training program which is comprehensive with Listening and Spoken Language skills training for about 3 years, along with auditory verbal therapy of 1 year duration.
The intensive Listening and Spoken Language (LSL) training program benefits the child immensely.
The age at which the cochlear implant is put largely influences the outcomes. The outcomes are better if the surgery is done early in age. The age period 9 months – 3 years give the best results with minimum LSL training.
Children who have had surgeries after 3 years of age need more training. Only auditory-verbal therapy for one hour per day is not sufficient.
Implant in one ear (unilateral) vs two ears (bilateral):
Bilateral implants are the best choice for a very natural acquisition of language and speech. Bilateral cochlear implants with good mapping and training, empower the baby to hear sounds as close as possible to that as heard by a person with typical hearing.
Listening from both ears is always advisable. If only unilateral implant is provided, it is advisable to fit a suitable hearing aid in the other ear for better outcomes.
- An excerpt from “https://www.nidcd.nih.gov/health/cochlear-implants”
Who should go for a Cochlear Implant?
Children having severe to profound bilateral hearing loss, and for whom hearing aids are of very minimal or no use.
Cost and Maintenance of Cochlear Implants
There are different models of cochlear implants. A low-end model for unilateral fitting costs around Rs. 8 lakhs inclusive of surgery and one year therapy (AVT). A high-end model may cost Rs.17 lakhs, as of September 2023.
The cost of maintenance is significantly higher than that of a hearing aid.
New processors would be introduced every few years, and the parents may be advised to upgrade.
Sometimes, the baby may lose the processor, or it may be damaged. The replacement of the processor of a single cochlear implant may cost Rs.3 lakhs or more.
Once an implant is fitted, the baby is wedded to that manufacturer for life.
AUDITORY BRAINSTEM IMPLANT
Auditory Brainstem Implant is useful where the auditory cochlea or auditory nerve is abnormal. It bypasses the auditory nerve also and is implanted at the base of the brain.