--that this is a peripheral nerve problem, rather than one associated with some problem in the spinal cord or adjacent nerve roots? Symptoms caused by peripheral neuropathy can be difficult to distinguish from those caused by spinal cord or nerve root compromise.

I should think that there should at least be some testing for peripheral nerve disorders. We have list of these at the Peripheral Neuropathy forum; one or the most comprehensive are the Liza Jane spreadsheets:

www.lizajane.org

Or at the forum here:

http://neurotalk.psychcentral.com/thread177.html

You probably should do some reading at the peripheral neuropathy section here anyway, and definitely check to see how extensive your non-imaging testing has been.