does anyone have cidp and myasthenia gravis?

dell was diagnosed with cidp at 19 months of age (dec ’05). we began ivig treatment and saw a very good response. he continued to improve with receiving ivig on monthly intervals. in june of ’06 we noticed his neck was gradually weakening. we began receiving ivig every two weeks with no improvement. the rest of his body began to weaken as well. in oct ’06 he was admitted for 3 days of back to back ivig and his steroid was increased. a test showed he was positive for myasthenia gravis but an emg tested negative for mg. he then began mestinon. his strength has increased but not to the level it was back in june. does anyone have a similar situation or have anything to share with us about his situation?