So, what is a bionic ear / an Auditory Brainstem Implant ?
The implant is similar in external appearance to a cochlear implant which most people have heard of 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 fused auditory nerves the device is useless as the sound can’t get through.
An auditory brainstem implant (ABI) is a small (4mm long) paddle with 12 electrodes (Medel) , although the Cochlear Brand uses 21 The paddle sits on the brainstem that the cochlear vestibular nerve attaches 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 uses electric acoustic brain response (EABR) testing to check the placement whilst still in theatre. We have seen a few videos of this procedure and its very tricky.
About 6-8 weeks later (once the swelling on the brain has gone down) the implant is activated. Some electrodes can cause a non auditory response – a tingling toe, cough etc. The audiologist turns off any that cause discomfort and can also turn up or down the electrodes depending on the results that they achieve. From then on there will be further mapping sessions, carried out in specialist audiology centres to fine tune the device to give the patient the best possible access to sounds.
Externally the patient wears 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.