Rituximab in chronic inflammtory demyelinating polyneuropathy associated with diabetes mellitus

Background: Some patients with diabetes mellitus (DM) develop a peripheral neuropathy indistinguishable from chronic demyelinating polyneuropathy (CIDP). Immune-mediated mechanisms are involved in the pathogenesis of demyelinating neuropathy in DM and in CIDP. Immunotherapy, including intravenous immunoglobulin (IVIg) is effective in idiopathic CIDP and CIDP-DM. Despite treatment with IVIg, CIDP may remain clinically active. It has been reported that CIDP may respond to Rituximab (RTX), a chimeric humanized monoclonal antibody against CD20+ antigen on B-lymphocytes. We reported a patient with CIDP associated with DM increasingly less responsive to IVIg who was treated with RTX.

Patient and methods: In April 2004 the patient experienced numbness of the toes and soles of the feet and unsteady gait. In December 2004, the disorder progressed to the point where he required a walking aid. The patient fulfilled the criteria for CIDP according to the Inflammatory Neuropathy Cause and Treatment (INCAT) group. The onset age of type 2 DM was at age 52 years. The patient received therapy with metformin and diet control. A treatment with an induction course of IVIg was started in December 2004. 1-day maintenance courses of IVIg were continued monthly. In September 2005 a relapse of CIDP was observed. A second induction course of IVIg was administered with no clinical improvement. The patient kept worsening. Treatment with RTX (375mg/m² body surface, once weekly for 4 weeks) was started. The patient demonstrate an improvement of walking capacities and sensory symptoms after 4 weeks. Neurological follow-up examinations performed 3, 6, 8 and 11 month after therapy revealed a stable disease course.

Conclusion: The clincal improvement and subsequent stabilization obtained with RTX in our patient may suggest this drug as an option in patients with CIDP and co-occurrence of DM. Further cases and a placebo-controlled trial are warranted to determine the role of this therapie in CIDP-DM.