Interest of Mycophenolate for CIDP Weaning

Inclusion criteria : * Patient older than eighteen * Written informed consent for study participation * Definite or probable CIDP according to EFNS/PNS criteria or atypical CIDP (need to meet clinical EFNS/PNS criteria and at least 2 criteria among the EFNS/PNS supplementary criteria) * Being responder (= decrease of at least 1 point on the ONLS score after IVIG) and dependent to IVIG (= increase of at least 1 point on the ONLS score after IVIG withdrawal or during the tapering period) * Having received at least 3 courses of IVIG * Negative pregnancy test for women of child-bearing age Exclusion criteria : * No social security benefit * Pregnancy or intention to become pregnant * Nursing mother * Recent or active VIH or hepatitis B or C , or lyme infections * Monoclonal IgM gammapathy with anti MAG antibodies or CANOMAD syndrome * Neutropenia \< 1G/L * Malignancy during the 10 years before the inclusion * Patients having received Mycophenolate * History of allergy to mycophenolate or placebo excipient * Patients having received immunosuppressive drugs during the 3 months period before the inclusion * Patients receiving : plasma exchange, magnesium hydroxide, aluminium hydroxide, cholestyramine