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Home arrow Environment arrow Inflammatory Disorders of the Nervous System: Pathogenesis, Immunology, and Clinical Management
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Pathology

Postmortem studies as well as MRI and ultrasonography have demonstrated involvement of nerve roots, plexi, and proximal nerve trunks, as well as focal involvement of more distal portion of peripheral nerves in CIDP patients [88, 89]. The classic histopathological findings include demyelination, remyelination (thick myelin sheath and onion bulb formation), endoneurial edema, and presence of inflammatory infiltrates (CD4, CD8 lymphocytes) in the perineurium and endoneurium [73]. Macrophages intercalate between the layers of Schwann cell membranes, including outer mesaxon, extending their elongated processes into the myelin lamellae and breaking them down [90]. Due to the focal distribution of lesions, up to 20% of biopsies may show no inflammatory changes. Only 10-50% of nerve biopsies show inflammatory cell infiltrates, due to the focal nature of the disease [90]; on the other hand, 20-40% only show features of axonal degeneration [73, 91, 92].

Immunopathogenesis

CIDP is an autoimmune disease as proven by its response to immunomodulatory treatments, presence of inflammatory infiltrates in the peripheral nerves, and development of a chronic relapsing EAN in animal models, similar to CIDP from the pathological and electrophysiological standpoint [93, 94].

Immunopathogenesis of CIDP is complex and involves both cellular and humoral arms of the immune system, affecting peripheral myelin. Breakdown in the blood- nerve-barrier (BNB), which protects the microenvironment of the nerve from exogenous proteins such as potentially pathogenic immunoglobulins, plays a key role in the pathogenesis of CIDP. Abnormal permeability of BNB can be detected via contrast enhancement seen in the MRI of the inflamed nerve trunks and plexi of patients with CIDP [95, 96].

Similar to AIDP, the target antigen remains unknown in CIDP, but unlike GBS, CIDP is characteristically not preceded by an antecedent infection. Although about a third of cases were preceded by an infection in a previous study [97], other studies have challenged that data by finding that the antecedent infections were present in only 10% of patients with CIDP, which does not differ from the prevalence of in the general population [98]. On the other hand, the onset has not been consistently linked to any one specific antecedent infection, with the exception of rare association of CIDP and HIV infection [99, 100]. CIDP has been rarely reported in association with malignant melanoma, which is explained by presence of shared antigens, such as myelin-associated glycoprotein and different gangliosides, between melanocytes and Schwann cells, as they both are derived from neuroectodermal origin [101-104].

 
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