--but the term "idiopathic mononeuritis multiplex" is only a symptomological description--it doesn't otherwise have much value.

It simply describes that you have had multiple individual nerve pathways damaged enough to cause symptoms in the areas these pathways serve. And, of course, no cause has been found.

On the other hand, unless you've been seen at a tertiary center, I would doubt you've had anywhere near as extensive a work-up as you might need. In young women, a mononeuritis multiplex suggests possible autoimmume disorders, possible toxicities, or possibly nutritional deficiencies, for starters.

Have you had vitamin levels tested? Autoimmune panels done (especially for the anti-nuclear antibody variants)? Any reason to expect chemical toxicity and get testing done for heavy metals and/or organic solvents in tissue?

I would look over the Liza Jane spreadsheets, which were created to be about as extensive a listing of tests for neurological symptoms that the best minds could think of, and see what you;ve had done and not done (and the spreadsheets also serve as a handy guide to track results over time):

www.lizajane.org