My MG was definatively diagnosed with a tensilon test with Mayo's neuro opthamology. I was seronegative and EMG negative at the time, but my eye was drooping. The tensilon injection opened my eye right up and I was diagnosed MG. I had a 4 day workup when I was first diagnosed. Go in with a positive attitude and let them test you for everything (like they did me), I had MRIs, an MS spinal tap, all kinds of tests, I even caught all my urine for 8 hours walking around the campus, and in the end, I walked out with MG after 4 days of testing.