BCHE and myasthenia gravis: In the first observational study of Mouri et al. in 5 patients with refractory MG (moderate to severe disabilities despite thymectomy, high-dose prednisone, and cholinesterase inhibitors), PE combined with prednisone and azathioprine therapy improved symptoms, and the serum acetylcholine receptor antibody titer decreased to an average of 21% of the baseline level, and muscle strength enhanced simultaneously [16].