test for neuropathy, vasculitis

I have a twin sister who has vasculitis. She recently began to develop tingling in her feet and her doctor said this may be neuropathy and be a sign that her vasculitis has become systemic. She said the doctor mentioned some kind of test involving a needle to check for neuropathy but she didnt catch the name. I have only completed my first semester of a BSN so I had no clue what test she could be talking about. Do any of you have any idea and do you know anything about vasculitis because there seems to have been very little research done on this condition? Thanks for any info you can provide.