Myasthenic crisis with delayed recovery after plasmapheresis

We report on 2 elderly patients with myasthenia gravis in whom recovery from crisis was prolonged despite intensive plasmapheresis (PP). In both patients, the anti-acetylcholine (anti-AChR) titer failed to fall sufficiently after completing PP. These patients might have had antibodies that produced a more pronounced effect on the degradation of AChR, or the synthesis of AChR might have been reduced by aging. The anti-AChR titer did not correlate with a reduction of IgG after PP in 1 patient. Successful treatment was achieved by keeping the anti-AChR titer at a low level via the concomitant use of prednisolone with PP.