Alice is the best person to answer this question for you.

In Japan in 2003 scientists there did a study on patients with seronegative MG and the SFEMG. They reached the conclusion that seronegative MG will not always show on a sfemg. Angela Vincent was part of this study. It was published in a medical journal, however its never really been embraced with open arms by the medical profession. I dont know why.

The rest of the answer I can't give you, but its something to do with the way the electrical current runs through the muscle. Im sure someone who hasn't got a bout of brain fog will be able to help you.

It is incredibly frustrating as SFEMG is still held up as the gold standard, which clearly it isn't.

Love
Rach