--barring any obvious causes of nerve compression, such as certain heavily-engaged in exercises/athletics or blunt trauma, as if you could use a more comprehensive work-up to see, yes, if there is something more systemic going on here.

There are certainly systemic causes of neuropathy, many of them autoimmune or nutritional, that may present as multiple mononeuropathies that may wax and wane over time and show up in different body parts.

You might want to look at the following sites to get a sense of the many different possible causes of neuropathy and the testing that might be involved; I suspect you've likely only had a fraction of these tests as it takes real specialists to be familiar with many of them:

www.lizajane.org

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