I read an interesting article this morning about a study starting up in Boston that uses Auditory Brainstem Implants (ABI) on infants that are not eligible for Cochlear Implants. This was particularly interesting to me because (1) I had no clue what an Auditory Brainstem Implant actually was and (2) the possibility that Fiona might not be eligible for a Cochlear Implant hadn’t yet occurred to me (cue latest mini-freakout).
So I did some research and here’s what I found: In less then 1% of deaf individuals, the actual auditory nerve from the cochlea to the brain is damaged or nonfunctional (from wikipedia). If you saw my post on Cochlear Implants, you’ll see that the CI works by connecting electrodes into the inner ear and through the cochlea, bypassing the damaged ear “hair cells” and stimulating the auditory nerve directly, which then carries the signal to the brain. If the auditory nerve is damaged, then a CI can’t work.
This is where Auditory Brainstem Implants (ABI) come in. They work very similarly to the CI, but instead bypass the cochlea and auditory nerve to stimulate the brainstem directly, as shown below:
So why don’t people just do the ABI?
Well first of all, you’re now talking brain surgery so the complexity, risk and cost of the procedure is much higher. Secondly, the effectiveness (in terms of spoken word understanding) is at best equal to CI, and often less. So in other words, more risk for less results. But, if no other options exist, this may be a last hope.
The scope of ABIs done is far less then CI: 1000 adults worldwide for ABI vs. 200,000 for CI. Also, until recently ABIs were only FDA approved for children over 12 years old. The study cited above is new in that it is being performed on infants, which should be interesting to watch.
As of today we don’t know the cause of Fiona’s deafness or if she would not be eligible for CI. Tomorrow we visit the ENT (Ear, Nose, Throat) doctor for the first time, and while we don’t expect to have all the answers then, we do expect to know the next steps.