Demyelinating disease is a group of diseases in which the myelin sheath is lost or thinned while the axon is relatively intact. The pathological changes are the loss of myelin from nerve fibers while the nerve cells remain relatively intact and the transmission of nerve impulses is impaired. In acute demyelination, the nerve sheath can be regenerated more rapidly and completely, with little impact on functional recovery. In chronic demyelinating neuropathies, functional recovery is incomplete because of repeated demyelination and regeneration of myelin sheaths with marked proliferation of neurofilm cells, thickening of nerves, and loss of axons. The etiology is unknown and may be related to the following factors. 1, genetic factors: there are more HLA-A3, -B7 and -DW2 antigen-positive patients in white European and American patients. 2, human geographic factors: the disease is more common in cold and temperate zones, and less common in the tropics. Europeans have a high incidence, while the prevalence of the East and Africa is lower. 3, infection factors: there were suspicions that measles virus, herpes virus and HIV virus are related to this disease, but even the application of molecular biology methods to detect the genome of the virus in the lesion and the surrounding brain tissue, but also failed to reach a clear conclusion. Animal experiments have shown that injection of brain tissue components or rabies vaccine can cause demyelinating lesions, suggesting that the disease may be an allergic disease induced by multiple factors. CD4T (helper) and CD8T (suppressor) cells can be detected in demyelinating lesions, however, the exact pathogenesis remains unclear.