Not always. There may have been, but your doctor didn't tell you as most laypersons aren't familiar with medical terminology, and the fear factor can be proportional to the length of the medical term.

You can always ask to see your medical records for your doctors "official" DX—or just ask.

If there's nothing more than "peripheral neuropathy" I think it's probably safe to assume the doctor believes it's idiopathic, which just means he doesn't know.

Doc