Daniella,
The center in Chicago may well be the Jack Miller Center for peripheral neuropathy founded by an idiopathic PN sufferer some years ago. They are part of the University of Chicago hospital system which is very good. The link follows
http://millercenter.uchicago.edu/
If Sue's suggewstion about Henry Ford Hospital doesn't work ourt maybe you could contact the Jack Miller Center. They do both PN research and clinical evaluations. The website has some really good links to explain the types of PN, causes, diagnostic procedures, etc.
Best of luck - hope you get some real relief soon.
Alkymst