Hello @rlipper, Welcome to Connect. Sorry to hear your father-in-law hasn't received much help. He's not alone not having a cause for his neuropathy. I also have an idiopathic diagnosis but they suspect mine might be genetic. One site that I have found quite helpful when trying to find out how to manage my neuropathy is the Foundation for Peripheral Neuropathy - https://www.foundationforpn.org/living-well/.

Does he have pain with his neuropathy or is it just loss of leg use due to numbness and weakness in the legs?