I used to know someone who hiked in the winter who had this. I've also heard talks by Dr. Murray Hamlet, who does (or did) cold research for the army. Hamlet claimed that you could treat Raynauld's by standing outside in winter with minimal clothing and your hands in warm water for 10 minutes at a time. It was supposed to retrain your capillaries to open when your body was cold. Not sure if the cure was worse than the disease.