Chronic inflammatory demyelinating polyneuropathy: Clinical subtypes and their correlation with electrophysiology

Abstract

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is currently classified into "typical CIDP" and other variants, such as "multifocal acquired demyelinating sensory and motor neuropathy (MADSAM)". Typical CIDP is a classic form, clinically 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, presumably because of the lack of the blood-nerve barrier in these regions, and this could be responsible for the "non-nerve length-dependent" distribution of muscle weakness. Furthermore, the safety factor of impulse transmission is physiologically lowered by axonal branching in the intramuscular motor nerves, and therefore, conduction block develops more readily in motor axons than in sensory axons, leading to motor-dominant polyneuropathy in typical CIDP. These findings suggest the importance of humoral immunity in typical CIDP. In contrast, MADSAM is characterized by multifocal demyelination in the intermediate nerve trunks with preservation of the nerve terminals/roots, and such distribution of lesions should result in multiple mononeuropathy or asymmetric polyneuropathy. In MADSAM neuropathy, cellular immunity might be predominantly involved in the breakdown of the blood-nerve barrier at the site of the conduction block. Clinical features are likely to be determined by the distribution of demyelinative lesions, and probably reflect the different immunopathogenesis of each CIDP subtype. This review focuses on clinical-electrophysiological correlation in the subtypes of CIDP. © 2011 Japanese Society for Neuroimmunology.