Chronic Inflammatory Demyelinating Polyneuropathy.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is immune-mediated neuropathy defined by clinical progression for more than 2 months, and electrodiagnostic evidence of peripheral nerve demyelination. However, there are several clinical phenotypes, classified into "typical CIDP," and "atypical CIDP" such as "multifocal acquired demyelinating sensory and motor neuropathy (MADSAM)." Typical CIDP is a most common form, characterized by symmetric proximal and distal muscle weakness and motor-dominant manifestation. In typical CIDP, demyelination predominantly affects the distal nerve terminals and nerve roots, where the blood-nerve barrier is anatomically deficient. These features suggest antibody-mediated demyelination in typical CIDP. By contrast, MADSAM is characterized by multifocal demyelination in the nerve trunks, and such distribution of lesions results in multiple mononeuropathy or asymmetric polyneuropathy. In MADSAM, cellular immunity is likely to be involved in the breakdown of the blood-nerve barrier at the site of conduction block. Clinical features are probably determined by the distribution of demyelinative lesions and reflect the different immunopathogenesis of each CIDP subtype that would require different treatment strategy.