Seronegative

My daughter Vanessa aged 15 was diagnosed 3 months ago by tensilon test. Her achr was negative and her musk test result is not back yet.I'm concerned that if her musk is neg. also that we won't be sure which treatment offers best results. Currently takes Mestinon 60x3 per day. Fatigue is very severe. Eyelids and double vision have improved but she chokes and gags frequently. She had one incident with breathing difficulty but this was worsened by a chest infection and improved with oxygen and antibiotics.
Neuro has recommended thymectomy - have results been good for sero-neg patients?
If Musk is also neg. what treatments have shown best results?
Should her thymus be investigated?
Can we do anything to alleviate fatigue - she is receiving home schooling - too tired to go to school?
When Vanessa gets upset she has quite sever muscle twitching and overall muscle weakness-is this normal?
Any advice will be most welcome!!

[CCF-Neuro-M.D.-CS]

Ther are several issues:
1) Regarding thymectomy, no one knows how seronegative patients respond compared to others. However there is growing data within the literature which suggests that MUSK positive patients do not respond to thymectomy. But there is no definitive study investigating this.

2) I do believe that a CT scan looking at the thymus to exclude a mass or overgrowth would be recommended.

3)She appears to be having symptoms which are not responding to Mestinon. To stabilize her condition and make short term improvements she may need treatment with intravenous gamma globulin or plasmapharesis (blood filtering). These can alter symptoms temporarily, and then a consideration regarding long term treatment can be made.

4)Regarding the diagnosis she should have an EMG test (muscle and nerve test) with repetitive nerve conduction studies, and if this is normal a single fiber EMG. Single fiber EMG is typically positive in 95-98% of patients with MG regardless of the presence of antibodies or not.

5) Perhaps a consultation at a large academic center would help to make a treatment plan which is best for your daughter. Good luck