PMR (polymyalgia Rheumatica) is an inflammatory autoimmune disorder that causes pain in your joints and muscles. It is extremely painful and upsets your quality of life. Don't know how else to describe it, but if you have it , you know it. Prednisone relieves it almost immediately. There is no cure for it, but it can be manageable. It can resurface at any time which means upping the Prednisone mgs again. I'm sure John can explain it better. Hope this helps.