It took a long time for me to get a correct diagnosis for Turner Parsonage Syndrome. The onset of the nerve death was one of the most painful things I've ever experienced. At first it was diagnosed as bursitis, then rotator cuff. It was a physical therapist who noted that I had atrophy of my deltoid muscle. After some research I found the Nuro-Muscular clinic at Oregon Health & Science University in Portland, Oregon. They used an EMG test to confirm that the nerve from my spine to my deltoid was gone. The suspicion is that two things led to this event. One was a impingement of the nerve from a competitive game of table tennis, marked by two sharp incidents in my shoulder that day, and this coincided with the onset of a virus that I came down with that evening. A lot of folks were getting this virus, with symptoms of a fever and some body aches. The doctors concluded that the white blood cells found the inflamed nerve while they were wiping out the virus, and took the nerve out along with the virus. My doctors told me that exercise would not help the deltoid, as it was like trying to turn a lamp on and off without it being plugged in. If the nerve grew back, then exercise would be helpful. I would add that careful exercise would probable help the surrounding muscles to support the shoulder. I was lucky, and after about 18 months my nerve had grown back, and I recovered about 95% of my nerve and muscular ability. I feel that some physical work and some exercises I did while I was lacking my deltoid actually added some injury to my shoulder. So be careful about not over-using weakened areas.