How does a Cochlear implant work?

Since Matthias' C.I. (Cochlear implant) surgery last week, I realized that many people actually have no idea what a cochlear implant does. 

The first step in getting a cochlear implant is surgery.

Basically, during the surgery, a device is place under the skin (The white #3 in this pic). There is a string of electrodes that is connected to this device which is fed through the cochlea. The cochlea is blue in this picture. That white sting is what is inserted. 

This might surprise you (it did me), but this surgery takes about 2 hours per ear. A lot of times, doctors only do one ear at a time. If they do not work, they want to preserve hearing in at least one ear. Once a cochlear implant is placed, you cannot go back to a hearing aid.

Matthias did not have any hearing to preserve, so we did both ears.

This is what the bandage looks like after surgery.

 After 24 hours, you remove the bandages, and there are steri strips underneath.

A lot of people assume that at this point a person can hear.

That is not the case. At this point, you must allow the body to heal.

They used to wait 4-6 weeks, but now they only wait 2 weeks.

2 weeks after surgery, after the surgeon has agreed, you meet with you audiologist to get "activated".

These "processors" are actually what helps the person the hear.

The one on the left is worn behind the ear. The one on the right can be clipped on clothing, arm bands, head bands etc. The one on the right can also be made water proof.

 This is a picture of a child wearing the water proof one.

 This is a picture of a child wearing the behind the ear one.

Matthias will be getting both types for each ear. So, he can wear either kind.

Now how do these processors help a person with cochlear implants hear?

1. A sound processor worn behind the ear or on the body, captures sound and turns it into digital code. The sound processor has a battery that powers the entire system.
2. The sound processor transmits the digitally-coded sound through the coil on the outside of your head to the implant.
3. The cochlear implant converts the digitally-coded sound into electrical impulses and sends them along the electrode array placed in the cochlea (the inner ear).
4. The implant's electrodes stimulate the cochlea's hearing nerve, which then sends the impulses to the brain where they are interpreted as sound.

So, will Matthias hear instantly once they turn the processor on?

In theory, yes, he will, BUT there is a catch. The brain still has to interpret what is being heard. This means a path from the auditory nerve to the part of the brain that interprets sound must be formed. For a person who has already heard before, the path is mainly formed. They just need to build a small bridge from "normal hearing" to what is called "bionic hearing". For someone like Matthias, however, this process is much more challenging.

I like to use metaphors, so here it goes.....

Imagine you are standing in this field. Where you are standing is where the sound enters the brain. See that tree over there? Far in the distance. Imagine that is the part of the brain that interprets sound. You have to find a way to build a path to get from point a to point b.

Some people make this seem simple because they may have a piece of heavy equipment to clear the path. 

With a machine like that, you could clear a path large enough for a semi truck in no time flat.

Other people may have something like a tiller to create their path.

With this machine, you could still build a decent path, and you could do it rather quickly, but there is no way a semi truck would fit through the first time you went through. Plus it would take a bit more effort to clear the path.

While other still have a small and simple weed eater to create their path with.

With this simple hand held tool, you can still clear the field, but it will not be an easy task. After a short time, you could walk through or maybe even ride a bike, but there would be no semi trucks riding through any time soon.

Why do I mention a semi truck?

Well, here is your answer. The more complex a sound, the larger path it needs to get through. A horn honking, something breaking, etc may be equivalent to a bike going through the field. Meanwhile, a more complex sound like a instrument or tune may be something like a car traveling through the field. Something super complex like language is equivalent to a semi truck driving though the field. Depending on the "tool" you are using (how quickly your brain adapts), and on how quickly your brain becomes exhausted will make a huge difference in determining how long it takes for a person to know what they are hearing. It can also make a huge difference in whether or not a person will understand speech and how long that will take. 

Some people may never be able to make a complete path. There may be a river, road block or something in the way. They may be able to get by on foot (meaning they can hear simple non complex sounds), but their semi truck (language) may never make it through (they may never develop language). 

The older a person is when they start communicating has a major effect on which tool they are using and their likeness of having a major road block. 

Doctors on not optimistic that Matthias will ever speak and understand language.

He does not have any communication yet, and he is almost 8 years old.

In the case of cochlear implants and forming the path of communication, Matthias' delays in development could benefit him. Because he is still learning things that 1-2 year olds are learning, his brain may pick up and interpret sound easier than a "typical developing" child his age. There is only one way to find out..... Trial.

I will keep you all posted on Matthias' progress.

His activation date is November 10th