@rwinney Good article. I believe these are the small unmyelinated fibers (as are the heat and pressure sensors of our peripheral nerves). As such, these small nerve fibers often get symptoms first. A thorough neurological exam should reveal these deficits. Often things like difficulty focusing eyes, IBS symptoms (some cases), orthostatic hypotension (almost fainting when you stand up), etc. are overlooked by patients focusing on their other chief complaint(s). If symptoms are serious see a neurologist first.