On Mon 02 Aug, janet paterson wrote:
> At 15:37 1999/08/02 +0200, you wrote:
> >Hi Brian!
> >
.
>
> how about a pallidotomy operation
> where the cells that have 'gone haywire' are zapped on the spot?
> along with the dyskinetic [?] movements
> seen it happen [on tv]
>
> jp
>
>
> janet paterson
> 52 now / 41 dx / 37 onset
>
Hello Janet. I imagine that you are thinking that:
1/ The patient has dyskinesias
2/ The Surgeon partially severs some nerves
3/ the Dyskinesias stop
4/ Those must be the nerves which cause dyskinesias.
QED
There is a bit more to the story however (wouldn't you know it) because
the source of the dyskinesias is in the Substantia Nigra - all PD symptoms
start from there) and the place where the surgeon makes the lesion is in
the Globus Pallidus (that's why it is called a Pallidotomy) which is nowhere
near the Substantia Nigra. To understand what is going on, you need to
consider the whole of the muscle control system, from the decision of the
brain to ,for example, move my thumb: This is roughly what happens;
1. A signal goes from the brain to the SN, saying release some dopamine
to lubricate certain synapses.
2. The electrical signal goes out from the brain, which actually conveys
the message - move thumb
3. There must then be all sorts of signals flying about: ( where to?,
how fast?, what do I do when I get there? etc.
4. This brings into play a vast array of sensory networks which compare
the position of the thumb against where the brain told it to go.
(the error signal).
5. The nerves carrying the error signal back to the brain do go through
the Globus Pallidus and I believe that it is these nerves which the
surgeon cuts.
It's fascinating, but I don't think it tells us about dyskinesias.
Regards,
--
Brian Collins <[log in to unmask]>
