[Neurological manifestations in cryoglobulinemia]

Cryoglobulins are immunoglobulins that persist in the serum, precipitate at cold temperature and resolubilize when rewarmed. Type I is often associated with hematological disorders. Type II and III are mixed cryoglobulins, composed of different immunoglobulins with a monoclonal component in type II and only polyclonal immunoglobulins in type III. Mixed cryoglobulins are associated with connective tissues or infectious diseases. Hepatitis C virus is involved in most of previously called "essential" mixed cryoglobulinemia. Dermatological, rhumatological, and nephrological manifestations are the most frequent, and neurological complications are found in 20 percent of cases. However, in mixed cryoglobulinemia with low cryoglobulins level, neurological signs may reveal the disease. Ischemic central nervous system complications are rare, but sensory, axonal, peripheral neuropathies or sensory and motor multiple mononeuropathies are more frequent. Prognostic and treatment depend on association with hepatitis C, and presence of vasculitis lesions in the nerve biopsy.