--take a look at this site (written in "doctorese", but very comprehensive nevertheless):
http://www.neuro.wustl.edu/neuromusc...tml#idiopathic
"Idiopathic" small-fiber snesory neuropathy is one of the most common presentations, although many neuros now believe that some form of autoimmune response may play a role in those who do not have undetected impaired glucose tolerance:
http://www.thecni.org/reviews/13-2-p07-treihaft.htm
http://www.dcmsonline.org/jax-medici...uropathies.htm