I have had this arm-itch (brachioradial pruritis) since 2003, my best friends are ice-packs. Going to Yoga 3 times per week, was a miracle , the arm-itch went away... so another year passed and silly me quit going to Yoga, now the arm-itch is back again the past year. I just returned to Yoga with hope that it will go away again.
If yoga doesn't work this time, I will go to the NUCCA who apparently may help this problem, read up on NUCCA (Chiropractic) I shall keep you posted.