It is called syncope…
I have it as well. When going from low to high, such as a sitting position and standing up, for those affected, there is a sudden drop of blood pressure that makes you dizzy. Also when reaching high and coming down will do the same.
But my CIDP affected my autonomic system. And yes, they did a skin biopsy which showed “small fiber atrophy”, meaning the CIDP was hitting my autonomic system. It has hit many of the nerves controlling my organs and processes, (i.e. nerves controlling the heart causing tachycardia, it hit the phrenic nerve which controls the diaphragm which makes it difficult to breathe, and hit my swallowing process making me choke when I eat, etc.).
The syncope came after it hit my autonomic system, and just simple bending and standing up can make me see stars.
Hope this helps.