Acute neurological worsening after Rituximab treatment in patients with anti-MAG neuropathy

• Peripheral neuropathy with anti-MAG monoclonal IgM may be improved by Rituximab.
• Acute worsening after Rituximab has been reported in 10 cases including our 3 patients.
• It may occur even in patients who have already received Rituximab without problem.
• It is unpredictable and severe and recovery may not be complete.
• This should be considered in making treatment decision.

BackgroundPatients with peripheral neuropathy and anti-MAG monoclonal IgM may respond to Rituximab, a humanized monoclonal anti-CD20 antibody.MethodsWe report on three patients with peripheral neuropathy and anti-MAG monoclonal IgM who deteriorated under Rituximab and reviewed seven previously published cases.ResultsWorsening was acute and severe, and occurred during the treatment period. All the patients improved after deterioration but at final evaluation only one was improved comparatively to baseline, five were worsened and four were stabilized. Deterioration was not clearly associated with an increase of the anti-MAG antibody titer. Two patients received Rituximab prior or after the course which induced worsening without adverse reaction.ConclusionAlthough rare, acute worsening of the neuropathy can occur after Rituximab. The deterioration is however reversible within some weeks to several months.