Welcome to NeuroTalk!
I just wanted to mention that the other posts are quite old so you may not receive any responses.
I also wanted to mention that many years ago I had a friend who was treated very poorly in a psychiatric hospital and it was discovered many months later that she indeed had Guillain Barre Syndrome. She was being treated for Conversion Disorder. All that meant was that the initial doctor could find no physical reason for her extremely debilitating symptoms.
http://www.ninds.nih.gov/disorders/gbs/detail_gbs.htm