So, what is a bionic ear? How is this different from a cochlear implant?

You may have read recently in the news about a man who received a bioinic eye from the use of a brainstem Impant.  This is the same procedure only using the auditory brainstem rather than the visual brainstem.

The brainstem is around 5mm long and the Medel implant (pictured here) is just 4mm long, so precision is vital.

It is similar in external appearance to a cochlear implant but the internal workings are very different.  A cochlear implant works by inserting a coil into the cochlear which then interprets signals received from an external microphone and sends these to the auditory nerve.  With no auditory nerve the device is useless.  

An auditory brainstem implant (ABI) is a small (4mm long) paddle with 21 or 12 electrodes depending on the make (Evie's will be a Medel which has 12 electrodes as pictured above).  The paddle sits on the brainstem that the cochlear vestibular nerve would normally attach to.  The brainstem is at a sloping angle and therefore the surgeon has to place the implant in at an angle.  The brainstem itself is about 5mm long and therefore requires very steady hands and a skilled surgeon to carry out the surgery.  The surgeon will use electric acoustic brain response testing to check the placement whilst still in theatre.

About 6 weeks later (once the swelling on the brain has gone down) the implant will be activated.  This is done in hospital as there will quite often be other parts of the body that react to the neuro stimulation.  They will turn off any that cause discomfort and can also turn up or down the electrodes depending on the results that they achieve.  We will be very reliant on signals and cues that Evie can give us to determine what she is experiencing.  From then on there will be further mapping sessions, carried out in specialist audiology centres to fine tune the device to give Evie the best possible access to sounds.

Externally Evie will have a processor which is like a cochlear implant processor.  This will pick up external sounds via a microphone and then convert these into signals for the neuro stimulators in the implant.  It is really amazing technology.  It isn't the same as the sounds you or I hear but with a young brain she should be able to interpret them just as we do.  At the very least Evie will be able to hear normal every day environmental sounds and this will assist her greatly with lip reading and speaking.  The optimum result is that she will be able to access "open set speech" which will be more than I could ever have hoped for and that is what Professor Colletti is aiming for.