I also have idiopathic sensory motor PN causing numbness with poor balance with drop foot, yet no pain. However, I do have back issues with a diagnosis similar to yours. I was convinced that the PN was being caused by back issues L3 to S1. Various MRI's have my neurosurgeon and neurologist at Mayo saying yes you have back issues but back is not the cause for PN. Oddly enough, I've shown doctors that if I rub my lower back when walking, the speed in which I walk improves. I get this dumbfounded look and a...hmmm. Tens unit no help. Not a diabetic, only one in the family with PN. Walking any distance is an increasing problem.