Hi Tony. Welcome.

Yes I was diagnosed based on physical exam and my positive response to mestinon. They did all the tests - MRI, CT, antibodies, thyroid, SFemg - and none were indicative of MG, though I was borderline on 'jitters'.

That was 5 years ago now and I still take Mestinon. Lucky for me, all my symptoms have stayed about the same. I'm much better in the winter months (mild where I live) and much worse in the summer months....but that's 'normal' now and expected.