I have to jump in here. I've been to Mayo in Rochester, MN and I went to Johns Hopkins and in late 2021, I went to the University of PA and I've seen some great neurologists. All tests conclude in my case sensorimotor polyneuropathy (idiopathic). The answer is ... no cause....and I feel it is as frustrating on docs as it is on us. Doctors spend years in school to learn how to treat people with medical problems and little can be done for those of us with PN. I have lots of numbness and poor balance but I try to remain optimistic. I feel like many of us there will be no cure but perhaps the best we can do is figure out how to live our lives with it. Ed