Hi Barbara!

Just to make things more confusing....I have a normal thymus (as per CT scan), am sero-negative for AChR, was in the lower limits on my single fiber EMG, but have MG symptoms (ocular and general), and respond well to Mestinon. The good news is I have a great neuro (my second == the first was close to worthless) who has enough experience to treat each MG'er as a unique case. They told me MG is really difficult to diagnose (some folks go years without dx) and treat (because what works for some, doesn't for others).

The Mestinon was the determining factor in my dx. Because I responded so well to it, MG was 'confirmed' even when the standard tests were negative or inconclusive.

Hope this helps a bit,
Sue