Vitamin C is a complex and essential nutrient. Humans are the only mammal who cannot synthesize their own Vit C.

So we are dependent on supplements and foods for it.

The best source of information on Vit C is the Linus Pauling Institute ( which is great for all supplements).

http://lpi.oregonstate.edu/mic/vitamins/vitamin-C

Vitamin C is an antioxidant and helpful for inflammation, so with some PNs it is very useful. The severe neuropathy RSD (CRPS) responds to high dose Vit C for example.

Some PNs are caused by toxins, drugs, Diabetes, hypothyroidism, and many other lifestyle issues. Autoimmune factors are more common in women than men, and often are triggered by illnesses, and vaccines. Viruses and bacteria have protein sequences on their cell membranes which may mimic some human tissues. So when you get a Strep throat infection, you may have genetic issues and overproduce antibodies to this strep sequence, and then those excess antibodies may go to the brain and cause a movement disorder called Tourette's (Tics).... the is called PANDAs.
This is PANDAs in more detail:
http://en.wikipedia.org/wiki/PANDAS

This type of process is not going to be "caused" by Vit C. It is because people have a set of genes making it more likely. Vit C in fact helps prevent infections, and therefore would prevent some autoimmune reactions that way.

Some doctors believe that full body PN may be a result of a viral infection (or bacterial one), triggering too many auto-antibodies to that organism. This is why we see vaccine reactions... which is an overproduction response to a infectious agent.