Hi. It's great you're having a SFEMG. That should give the doctors a lot more information.

You are right to stop the Mestinon before the test. Often they'll tell you 12 or 24 hours, but there is a small study here: http://onlinelibrary.wiley.com/doi/1...20211/abstract
that shows that Mestinon in your system can affect the SFEMG results for longer than that.

When I had my SFEMGs (I've had three, because the first two we inconclusive) they put thin needles (very thin) in my arms and legs. I've heard that it's important to make sure you're warm while they're doing it (because a chilled muscle might yield a false negative). The needles themselves aren't bad unless the doctor hits a nerve, in which case you may ask him to move the needle. While the needle is in, the doctor will ask you to slightly clench the muscle and hold it like that. The whole thing takes about 45 minutes.

My third SFEMG got me a diagnosis, finally. The weird thing is that this one was done on the muscles of my face (around my eyes). Those aren't muscles that I've noticed any weakness in. The neurologist didn't seem to think that mattered. He also sent small pulses of electricity (painless) to make the muscles twitch instead of asking me to clench the muscles, but they tell me this is an unusual method to use.

I hope this helps. It's good to know what to expect. I hope you get clear answers!

Abby