Just to add my story, in case it's helpful.

I have repeatedly tested negative for antibodies (AChR, MuSK, LEMS, and recently LRP4). I had two SFEMG's that came back borderline. Then I saw an MG specialist, and he did a SFEMG on my face around my eyes, which came back strongly positive. This seems weird to me because I rarely have eye symptoms--I mostly feel the weakness in my arms, legs, and trunk. I have no eyelid droop, and brief double vision (a few hours) maybe three times a year. The MG specialist told me that the facial muscles reveal MG best even when there are no noticeable symptoms in that area. I don't really understand it.

I have heard that the SFEMG test is non-specific for MG, but I can never get a good answer when I ask what else a positive SFEMG can indicate. When I google, I get this list: motor neurone disease, polyneuropathies, polymyositis, and Facioscapulohumeral dystrophy. I guess my doctors have ruled out the others on the basis of my symptoms. I've had symptoms for nine years now, and I'm not getting worse.

So I have a tentative diagnosis of MG, but I still feel like I'm a mystery, because the following treatments have not helped me: Mestinon; IVIg; Imuran (several years); and Prednisone.

Abby