dbab: "it felt like my concentration or that 'part of my brain' was floating out of the back of my head - no pain though......"
dbab: I didn't reply earlier, because I figured my input would not be very relevant. However, I did have this experience when I had a nuclear stress test (to detect heart problems). I had told them I was very sensitive to many drugs and meds, and they asked me what I was experiencing at all times during the test. At one point, when they asked me, I said "it feels like my brain is at the back of my head" expecting the usual blank stare response - however, they assured me that this was one of the "normal" reactions. However, they did stop the test after that also - perhaps based on the results they were getting - not sure. I did ask what the solution was that they injected and they replied "adenosine" - for what that is worth, I have no idea, but just wanted you to know that I have experienced something similar. I was also glad that I had a friend to drive me home as I had a very spacy feeling afterwards for a while. All the best, and I hope you don't have any more episodes - these things can be so scary and not knowing what level of seriousness - I would maybe even call your doctor and speak with the nurse - check your blood pressure etc.