Deciphering the mechanism and spectrum of chronic inflammatory demyelinating polyneuropathy using morphology

Abstract

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a form of chronic neuropathy characterized by demyelination due to immune-mediated processes. In addition to the typical form of CIDP, several atypical forms, such as multifocal acquired demyelinating sensory and motor, distal acquired demyelinating symmetric (DADS), pure sensory, pure motor, and focal types, have also been included as subtypes of CIDP, indicating the heterogeneity of pathogenesis. The degradation of the myelin sheath by macrophages has been reported in CIDP and is considered to play an important role in the pathogenesis of this disease. By contrast, recent studies have suggested the association of autoantibodies directed against paranodal junction proteins, such as anti-neurofascin 155 and anti-contactin 1 antibodies, with subpopulations of CIDP patients. Although patients with these antibodies tend to manifest typical CIDP or DADS symptoms, such patients show unique clinical characteristics, such as a younger age at onset, sensory ataxia, tremor and poor response to intravenous immunoglobulin treatment. Classical macrophage-induced demyelination is not observed in patients with these antibodies, whereas paranodal dissection resulting from attachment of immunoglobulin G4 antibodies to paranodal junctions plays a pivotal role in the mechanisms of neuropathy. Therefore, two distinct mechanisms exist that lead to nerve conduction abnormalities from a pathological viewpoint in CIDP. Advances in the search for autoantibodies in CIDP might make it necessary to reconsider the classification of this disease from the viewpoint of antibody recognition sites.