Over the years, I have tried many times to find the statistics, and Leslie you are right, Google just can't find them. From my understanding, there are no statistics on pure idiopathic SFN, because SFN is so often named by its etiology. For example: Diabetic Neuropathy, Toxic Neuropathy, Alcoholic Neuropathy. They are all predominately small fiber neuropathies.

Here is a chart I downloaded some time ago from the Neuropathy Association. It is 22 pages of the types of Neuropathy. I was really surprised by all the varying types and subsets of PN. On the very last page, you will find the Idiopathic Neuropathies. It states that up to 1/3 of neuropathies are Idiopathic. Small Fiber is listed here, with unknown epidemiology.

http://docs.google.com/fileview?id=0...ODFjMTkz&hl=en