Idiopathic parasthesia.
Translation:
We don't know why, but she has a sensation of numbness or tingling on the skin.
Subtext:
It sounds more impressive with a fancy name, and this way you might think we know what we're doing when we tell you we don't...
Oh, yeah. I figured out a long time ago that "I don't know" comes across a lot better in Latin or Greek.
But I had already figured out they were no longer trying to find out what happened and just help her recover. Symptoms are cheaper to treat than causes in the short term, so that's what insurance pays for.