Cochlear implants appeared rather gimmicky when it first arrived. With misconceptions around its use, most people were apprehensive. Even doctors were doubtful. It promised everything, would it deliver?
What were the fears with cochlear implant?
*It can’t help, if you are born hearing challenged.
*It doesn’t help in speech development.
*It will make the child alienated.
*It’s no good for old people with hearing problems.
So what are the answers?Read on.
The Story from deaf to hearing, is it magic?
Cochlear implant started in the second half of 1980s.
Riddled by misconceptions and hype it was handicapped by the need for really motivated children and parents.
But like all life-changing things , cochlear implant stood the test of time with flying colors.
Children who were helped by cochlear implant make us smile.
They tell us how they hear.How they understand speech.It’s through their words that we learned about life , from no sound to a noisy world.
Who it helps?
- Post-lingual deafness in all age group
- Old people with profound age-related hearing loss.
- In Auditory Dys-synchrony
Cochlear Implant in Children
Postlingually deaf children.Children who have already developed speech and has lost hearing due to some disease like meningitis.
Best Age of cochlear implantation: before two and a half years. But it has been done as early as one year of age.
7 years is a watershed zone, after which Prelingual deafness has variable results.
The longer the child has an implant , the better is the speech recognition scores.When the duration of use of the implant is same, results are better with a lower age of implantation.The rate of expressive and receptive language learning is similar to that of hearing children.
Role of cochlear implant in presbycusis
Presbycusis or age-related hearing loss is also helped with cochlear implantation.It’s useful in elderly with profound hearing loss, which cannot be helped with hearing aid.
A world without sound can be lonely.More so in the aged population.
10% of normal ganglion cells ( approx.3500 cells ) are needed to recognize and understand speech.
The successful hearing outcome is seen with useful hearing.This helps in hearing rehabilitation of the aged.
Depression, anxiety, social isolation in both elderly and people with decreased hearing makes life more difficult.
Pure tone audiometry(hearing test) of 70 decibels or more for those planning for implantation in children and adults.
Cochlear implant in Auditory Dys-synchrony
Auditory neuropathy or auditory dys-synchrony is complex.
Children have variable hearing abilities.
Normal middle ear functions, otoacoustic emissions present.
But Brainstem evoked response Audiometry is unresponsive.
This means sounds passes from outside to the ear up to the nerve of hearing, like a hearing person.
But the communication between this nerve and the brain is distorted. The sound reaches the brain scrambled and makes no sense.
Why does this happen?
The sensory cochlear hair cells responsible for firing electrical signals in response to sound, do so dys-synchronously.That’s randomly without the syncing needed for understanding the generated sound.
Plain English: the rhythm of the electrical firing, is not right for your brain to pick up as words.
The action potential doesn’t develop properly in the cochlear nerve.This causes hearing loss This is variable depending on. the degree of dys-synchrony.
Initially believed that hearing aids and auditory amplification would be useless. But some children benefit from hearing aids too.
Cochlear implantation can restore synchrony by, by-passing cochlear hair cells and stimulating auditory nerve directly and synchronously.
The theory is good.
But research continues for strategizing treatment, in Auditory Dys-synchrony.
The next burning question:
1 implant or 2 implant:One ear or both ears?
With 2 implants pros:
Better speech understanding.
This is more obvious in a noisy environment.Better sound localization, the direction of sound detection possible only with hearing in both ears.
Cons of 2 bilateral implants:
Most importantly the cost.
The dedication required for several years of necessary post-implant speech training and follow up.It’s Definitely not easy.
Where do we stand now?
Some governments cover the cost.
Few individuals can afford the cost of the best grade of the implant for both ears.
Government is realizing the cost of the implant is value for money.It is less than the years of disability support a person will need.
In children should you use up both ears?
Over the years as technology improves, maybe they’ll be better options?
Should you give up the present for the future many questions still need answers
Can there be a significant bilateral vestibular injury?
With excellent imaging, experienced surgeon and God’s blessing this is rare.
Is it cost-effective?
The benefits outweigh the potential harm for many cochlear implant candidates.
Updated November 2018
Cochlear Implant: Who needs it? ( Part2)