I think the doctor tries to find a reason for the neuropathy mainly to look for a cure, to reverse it. This is a pretty small window of time, if they can find out, it is caused by blood sugar, or pinched nerve, etc. then it can be reversed. Since there are no cures for PN, all they treat is the symptoms. That being said, they find that there medical bag is quite empty of choices, so then they just try to mask the pain, with anti convulsants or anti depressants. At that point, the Dx is pretty much for the doctor to prove it is physical and not just mental... But maybe someday when they strt to find cures, then it might be worthwhile to know what causes it.