Fast=
1) autoimmune attack (including arthritis and tendonitis)
2) poisons (sudden high doses heavy metals) or pesticides/herbicides
3) gout (uric acid or pseudogout with calcium crystals)
4) vaccine injury (but these are autoimmune in symptoms)

In my experience PN itself, is slower in onset.
Secondary causes like diabetes, hypothyroid, are slower onset.

There are about 100 causes of neuropathies.