Hi,
Because whenever one stands normally there is decreased intravascular volume, which is compensated by simultaneous
vasoconstriction, which is impaired in autonomic failure.
Due to this blood accumulates in the legs and there is decreased blood to heart and then to brain. This sometimes leads to further activation of vagal nerve from the heart which sometimes may lead to a further decrease in pulse rate as well as leading syncope or
fainting which probably happened during the testing.
So in treatment, I agree with increased fluid intake, exercise and
Florinef. Because increasing intravascular volume will be helpful.
The drug-induced cause is less likely as she is not on any such drugs. It's important that you see
neurologist or movement disorders specialist as from symptoms like handwriting changes and slowness of movement, there is a possibility of underlying neurological disease which is causing all these symptoms.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Ivan R. Rommstein,
General Surgeon