Features of anti MuSK positive ab in MG (myasthenia gravis)

The presentation may be atypical with severe bulbar, axial, and respiratory weakness, with relative sparing of extraocular muscles. Patients may get worse paradoxically with Mestinon, may have an atypical or myopathic EMG, and respond, sometimes dramatically to aggressive immunomodulation eg. plasmapheresis, MMF steroids and Rituxan