We report a 67-year-old female of multifocal demyelinating neuropathy with persistent conduction block (Lewis-Sumner syndrome). The OKT4/8 ratio and the T-lymphocyte blastogenesis were decreased and ...the anti-myelin IgG antibody was positive. These im-munological abnormalities may relate to the pathogenesis of this disease. We treated this case with immunomodulating agents and following resuls were obtained, 1) Admin-istration of oral predonisolone (PSL) improved conduction block, but the hand grasping power did not change. 2) Combination of PSL and cyclophosphamide (CP) was applied. Again the conduction block improved furthermore but the hand grasping power did not improve at all. But after the stop of the CP therapy becase of the decrease of white blood cell, the conduction block and hand grasping power became worse. Therefore we concluded that the combination therapy PSL and CP was somewhat effective, but CP lim-ited for its hematological side effects. 3) We then treated with the combination therapy of PSL and mizoribine (MZB) which is reported to be low toxic. She showed improve-ment of the conduction block and anti-myelin IgG antibody became negative. But the hand grasping power decreased gradually. MZB showed no side effect, but insufficient effect. 4) Now, we have been treating the patient with y-globulin, but the effect has not been obtained.
