Actually, Mestinon gets out of the system rather quickly!

Have you had any general tests done, like a comprehensive chem panel, thyroid, B12, vitamin D, etc.? If not, that would be a good idea. MGers often have other issues or other AIs, unfortunately.

MuSK, eh? Well that can be quite a different type of MG. No wonder you had that reaction to Mestinon! Check this out.

http://neuromuscular.wustl.edu/synmg.html

http://neuromuscular.wustl.edu/mtime/mgdrug.html#musk

Is your neuro a MG expert? MuSK can be tricky, so they might need to do a little research if they aren't real familiar with it. It might be worth it to consult, even if over the phone or email, with a neuro who does have experience with treating MuSK.

Have you had a chest CT to look at your thymus gland?

Rituximab might work for you. Dr. Charles Harper (MG expert) from Mayo in MN has treated MG patients with that (he has an email listed on their website).

You should do a lot of research before you decide on what to do. And if you have a family history of cancer, that's important to tell your neuro, too.

Maybe you could do a post calling on help from fellow MuSK patients, to see what has worked for them!

Annie