I believe that is an excellent question...

I am going to explain it simply by comparing us who are tremulous -shakers
as we are electric -Walt Whitman had a great title to one of his poems -
I sing the body electric... we are indeed.

okay -if we were lamps and everything was working when we hit the switch or pulled the chain to turn on the lamp -it would turn on automatically,
yet if the cord was bad because it was only hanging on by a few fibers
or the light bulb was not in the socket because it had become abit loose,
you would see it may not turn on or if it did it would blink off and on ...
in our bodies we have synapses they signal the electricity in the body
to wire a message to the hand to hold a glass, but the signal is impaired because their is a short in our bodies, we could be short in many different areas: therefore we could easily drop that glass glass sending it crashing to the floor, because the signal misfired and was lost -it possibly incurred a delay
before we actually get the signal...

we do this even in our hearing -because I would ask people to repeat they thought I was deaf or was not paying attention to them
but the most irritating part is - I am trying very hard to hear them -
but I lose words -and some doctors do not know this -only the great doctors
who are brilliant - seem to understand that it is a lost signal...

it you want a technical answer go to www.answers.com
and type in tremors and parkinson's disease...
http://www.answers.com/topic/parkins...oms?cat=health

also this is extra but for you -no charge...

some PD patients do not tremor -they just can't move -we call that - "freezing" -my good friend he used to ask me for my hand - I believe because my electronics helped him re-hook up... to the "live wire"
in my body... then he could walk again -


last week when the iceman/storm came through my area of the country,
the power lines were down because the weight of the ice on the trees
broke major limbs off trees - and they pulled down the power lines,
and the scary part about seeing this -I will never forget
the power line snapped I heard it buzz it caught the tree afire, and then
what lookedlike huge balls of fire that were bright red /electricity started rolling, a then kinda bounced themselves smaller my sister called 911 but it was busy -
so she called the state highway patrol because the glow of pink from these
huge fire balls cast a pink shadow in her house then immediately a crew showed up and turned off all the power on purpose?

for those