This is a good 2017 overview of Brachioradial Pruritus, Yosipovitch
It is by an academic dermatology with special expertise in itch and it appeared in a throwaway.
Dr. Yosipowitch's article brings one up to date with the current knowledge. To access it: Download Brachioradial Pruritus
Here is another overview of BRP that I posted ~ 3 years ago.