[tri-med] Aus Alex's Hearing and CAPD

Sorry that I have been MIA for the last week - its just been one of those
weeks!!!!!

I havent even had a chance to scan my mail - but I thought I would take a
quick minute to tintillate those who have been waiting for the results of
the research project Alex is part of. Well maybe not so much results but
some of the "I have learnt" stuff.

We had another all day session at the acoustic labs last week - for sitting
around doing nothing they sure are exhausting!!!

The doctor overseeing the study is now VERY interested in the hearing of our
triers :-)) because Alex's results are really confounding everyone. (BTW she
did her doctorate in Ohio)

The findings so far - to everyone's surprise Alex shows no evidence of CAPD.
Individually each ear is working very well. This all day session was to see
how both ears work together. On the surface it seems that they are.

They managed to duplicate all Alex's past results - the confusing stuff :-))
Behaviourally (VROA) he has a mild to moderate hearing loss. His ABR (brain
stem testing - no response needed from Alex) shows a moderate to severe loss
and his OAE's (hair cell responses - again no response from Alex) show a
severe to profound loss. This STILL confounds everyone, and it obviously
hasn't improved over time. Why? Why? Why?

Now for the stuff that I learnt. I have always asked whether the agenesis
(or hypogenesis) of the corpus callosum has had any effect on his hearing,
that is whether hearing crosses over and becomes contralateral or not.
Finally I got some clearer answers!!!!

In babies hearing is "basic" - it travels through the brainstem and the left
ear goes to the left side of the brain, the right ear to the right side of
the brain. This is what the ABR or BAER tests - the hearing as it goes
through the brainstem. As children get older their hearing "matures" and
starts to be processed by the brain cortex - the "white matter", so you get
cortical responses. Its a different pathway to the brainstem hearing and it
DOES become contralateral - that is it crosses over the corpus callsum and
is processed by the higher functioning areas of the brain. When this happens
the "brain stem" hearing fades into the background.

It has always been "thought" that children who are deaf, or severely
cognitively delayed do not develop this "cortical" hearing - the work of
this group of researchers shows that this is not so, that even babies and
children who are deaf DO have/develop cortical hearing - they are there and
are (they believe) more reliable than the the brain stem responses from an
ABR. Past work from this group (and I will type out the poster study for you
all) advocates using cortical responses instead of brain stem responses in
non verbal children because they are more reliable. (Holly I think that is
the "new" testing that they did on Morgan)

Back to this study though........

Consequently they feel that some children DO learn to hear. Holly the
overseeing doctor has seen children like Alex and Morgan before - she
believes us!!!!!!!!! She doesn't think that the ABR's are wrong............
They also agree that the approach a lot of us are using - pairing sound with
visual information really DOES help them to learn to hear or at least
understand what they are hearing and develop the cortical responses.

So far what they are seeing in this particular study is that children with
complete ACC do not develop contralateral hearing but they still have
cortical responses. So more mature responses still develop even with ACC its
just not contralateral. She didn't say whether the other kids had CAPD as a
result or not but I got the impression that they did.

Alex IS using those fibres of his corpus callosum that are there - for
hearing at least. The neurologist has always thought that there was so few
fibres there and because of the type of fibre (posterior fibres - thought to
not be used) that they are that he wouldnt.

What was interesting is that there is a major difference in the type of
brain wave that they are seeing from each ear. The left ear shows a very age
appropriate response, that crosses over well. The right ear (the one that is
"more deaf") is very immature.

Sadly what this doesn't tell us is why...........
Is it because of the mosaicism? (possible - one side is more effected than
the other)
Is it because he is deafer in that ear and so it hasn't matured as well?
(possibly not because up until recently he had reasonable good hearing in
that ear)
Is it because of myelination issues? (possible as I stopped the Efalex about
18 months ago which the researcher thought was interesting)

Interestingly as well the testing showed physically what we are seeing with
regards to Alex's deterioration. When Alex was younger he was a dawn to dusk
child - always on the go. Last year he started to fatigue about 2 or 3 in
the afternoon. No biggy at the time - we just thought the learning at school
was tiring him out.

This year we started to worry though - when the 2 or 3pm moved up to 11am.
We saw this happening with the physical deterioration as well so presume
that somehow they are related......... but always questioning whether what
we were seeing was accurate. What they saw however in the testing is that it
is accurate - at about 11am his attention fades and his brain shuts down. He
actually starts to produce sleep waves at 11am!!!

So no real answers as yet and I am REALLY eager to get the full analysed
results, but at least I can stop bashing my head on the CAPD wall and start
looking elsewhere. We have also been doing the neurospych battery of testing
(that was emotionally painful, for me, and I will do a separate update on
that one) - and both the neuropsychologist and the research group are going
to share the info that they have gathered on Alex (the neuropsych also saw
this "switch off" from Alex - so that is good!!) and see if together they
can help us work out what is going on and why we are seeing such marked
deterioration in the master. That doesn't guarantee any answers on stopping
it, but it may help, can't hurt anyway.............

A rich child often sits in a poor mother's lap.
  -- Danish Proverb

Keep Looking for Rainbows!!!
Karen, Mum to Alex (8, T-18 mosaic)
Sydney, Australia
http://members.optushome.com.au/karens
http://www.trisomyonline.org

                  Building ___ooOOoo__ Rainbows
                       www.trisomyonline.org
                  Families Helping Families On-line

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