Thank you for this idea. I just tried it sitting in front of my computer. It feels good. I usually touch my toes in the shower after I've been in the shower for a few minutes. I take my shower as hot as possible. Then I slowly turn down the hot water until I can't stand it anymore. It's refreshing and gets me going.

I've been getting my chiro to stretch my right leg and it helps. I've even put my foot between the stair railings and turned my foot to right outwards. This helps.

For me the relief happened (happens) within minutes of starting the stretch. Now that I’ve included it in a daily, morning stretch routine; I rarely, like maybe once in a few months, have any arm itching. And if I feel anything coming on I stretch and it goes away.

Well, it’s been a couple of years now… I think, for me it was right away. As with the use of the traction table (in my post of how I discovered the effect of traction on my Puritis). The traction I was doing to help my sciatic pain in my foot, while coincidentally experiencing arm itching from BP.
That relief was experienced immediately.
What took time, after developing the stretch, was the frequency I needed to use it. When I used the inversion table (for sciatica) I was on it for 15 minutes. Pain and itching were both gone. When I do the neck stretch to stop itching that is starting I do the stretch in 30 second intervals probably totalling 5 minutes. Keep in mind I have learned to do the stretches while sitting, standing, walking, driving… Almost anytime. The itching subsides in 5-10 minutes. I found the frequency was 2 or 3 times a day to fight off itching that I never aloud to get to the point of needing to scratch.
I then added doing my stretch to my morning stretches for my whole body. The neck stretch part of my time stretching is about 1 minute of a daily routine of 5 minutes stretching other parts of my body.
Since adding the stretch to my daily routine I don’t get itching anymore or maybe once every few weeks. But quickly get rid of it with a stretch. I would say I’ve found my cure. Creams and freezing techniques only dulled the itch for minutes. I believe because they try and deal with a symptom not the cause.
One caveat to all of this is the degree of Brachial Puritis you may have. If your condition is worse than mine I don’t know how much it will help. My hope is that you can find relief from this and other traction strategies available. There are inversion tables, inflatable neck collars and pillows that allow for some traction while you lay down.