--if you did show up slightly positive on the anti-sulfatide tests, that avenue should be purused. Certainly there are neuropathies of both large an small fiber that are the results of autoantibodies to components of peripheral nerves.

Do you know if you were also tested for the other known antibodies to peripheral nerve? The Quest/Latov clinical application has a list of these serological tests, as sometimes more than one can be found, and some are associated with monoclonal antibodies (M-proteins):

http://www.questdiagnostics.com/test...ripheralNeurop

http://neuromuscular.wustl.edu/nother/autoantibody.html