I bet you are confused. However, Mayo does have one of the best diagostic centers in the country. Do you have all records and tests presented to them from Chicago? You need to ask the doctors there, how they can say you are negative, with those numbers. I am not sure what LEMS is. Don't hesitiate to grill them on any issue you have. Keep a journal while you are going through the tests with all your quesitons. If you are not getting the answers you need to feel good about it, insist while you are there that they explain their positions clearly. I went there in 1980. Yes, several days of testing, but by the time I left, I knew exactly what was wrong, and was sent in the right direction for treatment. Hang in there. Repeting tests, is something I hope you do not have to experience. Most of the doctors I saw there were fantastic and did explain things to me very clearly. Also ask for the latest research, studies and trials that are going on once you get some defininative answers. They have access to all the latest research. You have to ask for that, but they will tell you. I wish you all the best. Let me know how you do. ginnie