You might be interested in something I've found recently.

The doctors have always said I have excellent capillary refill and circulation in my affected hand but I've always found that working with my hands over my head is very poorly tolerated by my condition and far more likely to lead to pain the following day.

I recently got a tens unit for the first time and have been experimenting (playing) with it. After a session the fingers on the "bad" hand turn quite cold and my blood pressure drops to normal. This can be over a 100 point drop total.

The stimulation just completely buries any low level pain.