Negative tests for myasthenia gravis

I was diagnosed with myasthenia gravis in July, 2005 based on clinical diagnosis with good results from taking Mestinon.  Over the past two years, my symptoms have worsened (but I also have had a very demanding full time job during this time which is too much for me).  I presently take 60 mg Mestinon (3 to 4 times per day) plus sustained release at night.  I also have IVIG treatments once every three weeks.  I tried Prednisone (40 mg/day) for a month (it was a great benefit) but put on 50 pounds and had high blood pressure so my neurologist took me off it.  The IVIG helps alot.  I still struggle much and the past year have developed shortness of breath when tired.  I went to academic hospital for EMG testing for a second opinion.  They had me go off Mestinon for two days.  When I did this, my symptoms escalated and I was very weak, although I was feeling well before I went off the Mestinon due to IVIG treatment 5 days before.  The EMG test was negative which the doctor there was very surprised about. He said before the test that the exam indicated mg.  After I left, I went back on the Mestinon and felt much better.  Could the IVIG treatment interfere with the EMG test?  How can the Mestinon work and the test be negative - that is my main question?  I am seronegative as well.  I am so confused now.  My neurologist here at home dismissed the negative results.  But the doctor who gave the test is not convinced I have mg due to the negative results and wants me to return in two months.

[sandy547]

ASK YOUR DR ABOUT MESTINON TIMESPAN 180 MG 3X DAY. THAT MIGHT HELP.

[DrNoopurMD]

Hi,

IVIG are intravenous immunoglobulins. In myasthenia gravis they act by diluting the host antibodies and in larger doses they suppress the production of autoantibodies.
Since the level of antibodies is reduced it is possible that IVIG may have influenced the results of EMG examination.
Since you are feeling better with mestinon it indicates that you are a myasthenic patient.
You can repeat the test after two months just to make sure. Take care!