Many years ago when I was seeing one of the doctors at the movement disorder clinic in Toronto he mentioned a small study they had just finished They had asked clinic patients about shoulder problems such as pain and stiffness in the years before PD was diagnosed. They were very surprised at the number of PWP who had such problems. Since then I have asked many PWP if they had needed treatment for shoulder pain and a surprising number said yes. I don't know if any such research has been written up in a medical journal. Perhaps one of the great hunters could do a search. Anne Rutherford