Idiopathic is frustrating. Knowing the cause is a kind of 'closure'.
Since there are over 200 known causes for PN, finding the right one
can be a 'needle in haystack' search. Endless testing to see that you are negative, since it is a process of elimination.
No one test finds a smoking gun.
But ideopathic or not, the treatments and meds are 95-99% the same !
Since there are about 75 meds currently Rx'd for PN - take your pick.
We are all different. We respond differently.
Same with response to the Rebuilder, TENS, Rejuvenator, etc.
But you must have a specialist neuro who has many satisfied PN patients.
Most neuros don't 'cut the mustard'.(no matter what they say- ask for patient referrals and ask the receptionist & nurse to tell you, about how many PN patients the doc sees - not 'a lot' but an actual estimate of numbers)
Good luck on your search.