--while there are certainly cases of neuropathy that involve more than the extremities, and these are certainly more common with acute autoimmune and/or toxic neuropathies, that degree of bodily involvement would also suggest an attempt to test for disorders of the central nervous system (brain and spinal cord), particularly for demyelinating conditions such as multiple sclerosis and acute disseminated encephalomyelitis (ADEM).

Have you had contrast MRI's of brain and cervical spine?