I had the Tensilon(endrophonium) test to confirm my diagnosis. I am double sero-negative and emg negative. You must have some weakness for the test to show definite improvement. Having eye ptosis at the time of the test is best but weak neck and shoulders work well too. I had both.
The test is done in the hospital in case of adverse reaction to the medication. I had a pharmacist standing by my bedside with atropine. My doctor said I did not need SFEMG to confirm my diagnosis further. Good Luck
Sandy