--the ESR/CRP results you're reporting does hint that thre's an inflammatory process going on, which can point to many things (including autoimmune disorders).

Evoked potential testing is when you're head is wired up and then you're presented with visual/auditory/tactile stimuli and the speed of your nerve impulses to and from the brain are tested--it can point to central nervous system demyelinating disease if these responses are slowed or patchy. Lumbar puncture, too, can point in this direction if certain proteins are found in the cerebrospinal fluid. Both of these are often used to look for conditions such as multiple sclerosis when brain or spine MRI's are equivocal.

They probably should be looking at far more antibody classes than the RH factor and ANA, though--there are so many others, including some that are specific to motor or sensory nerve.

A lot of us use the Liza Jane spreadsheets:

www.lizajane.org

These are probably the most comprehensive list of tests for processes that underlie neural symptoms (both central and peripheral) yet devised; very good for tracking tests results over time and suggesting tests to doctors they're not likely to think of. (It does sound as if your work-up has not been as extensive as it needs to be.)