Rituximab in cryoglobulinemic peripheral neuropathy.

Type II mixed cryoglobulinemia is sustained by an oligoclonal production of IgM sharing rheumatoid activity and can be associated with renal, cutaneous, rheumatologic or neurological manifestations. Peripheral neuropathy is a major cause of morbidity in hepatitis C virus-associated mixed cryoglobulinemia and is often refractory to any treatment. Rituximab induces a selective depletion of IgM-producing B cells, and both case reports on monoclonal IgM-related polyneuropathy as well as studies on small series of patients with interferon alpha-resistant mixed cryoglobulinemia have suggested that it may be beneficial. Thirteen patients affected by type II mixed cryoglobulinemia with polyneuropathy were treated. Rituximab was administered intravenously at a dose of 375 mg/m(2) on days 1, 8, 15 and 22. Two more doses were given 1 and 2 months later. No other immunosuppressive drugs were added. Response was evaluated by assessing the changes in the clinical neurological condition, in electromyographic indices and in laboratory parameters (including cryocrit, viral load, complement levels and rheumatoid factor) over at least 12 months. Sensory symptoms disappeared or improved following treatment. A significant improvement in the clinical neuropathy disability score was observed. Electromyography examination revealed that the amplitude of compound motor action potential had increased. Viral load did not significantly change. Side effects were negligible. In this open prospective study, rituximab appeared to be effective and safe in the treatment of patients with type II cryoglobulinemia-associated neuropathy.