The 10% meat of the book presents evidence the brain has the ability to control bloodflow to extremities. For example, we all know an embarrassed person can blush red in the face due to increased bloodflow caused by the brain processing the emotion of embarrassment. And reproductive arousal certainly involves bloodflow to various regions (not just genitals, but also lips and nipples for women, etc.).
So the theory is that the brain can restrict bloodflow to the arms which causes the numbness and burning that so many with RSI wrist/hand pain experience. The brain does this to us in response to us not processing certain negative emotions. In my case it was abuse from a parent I never consciously thought about. The book goes into stories such as a woman who was sexually abused by her father who, once she began consciously processing her hurt and rage, literally started crying out the chronic pain in her back. I had a somewhat similar experience, but slower and less dramatic. I had tremendous anger at the abusive parent and telling myself "I AM MAD AS F---ING HELL" made the pain go away.
Before this I literally tried thousands on ergo equipment, tried stretches and exercises and pushups and all that, none of it worked. It was my brain causing the problem, and my reluctance to not see it as a brain health issue made my healing process much slower.