[Acquired demyelinating neuropathies]

The acquired demyelinating polyneuropathies with either acute or chronic clinical presentation are considered autoimmune disorders. The Guillain-Barré syndrome is viewed as an acutely reactive and self-limited autoimmune disease, triggered by preceding bacterial or viral infections. There is a particularly strong association with the gastroenteric pathogen, Campylobacter jejuni, and with Cytomegalovirus and Epstein-Barr virus. It is likely that immune response directed towards the infecting organisms are involved in the pathogenesis of Guillain-Barré syndrome by cross-reaction with neural tissues. In the susceptible individual, the infecting organism induces humoral and cellular immune responses that, because of the sharing of homologous epitopes (molecular mimicry), cross-react with ganglioside surface components of peripheral nerve. Immune reactions against target epitopes in the Schwann cell surface membrane or myelin result in acute inflammatory demyelinating neuropathy (90% of cases); reactions against epitopes contained in the axonal membrane cause the acute axonal forms of Guillain-Barré syndrome. Immunomodulation with infusions of IgG or plasma exchange treatments effectively foreshorten the disease course. The immunopathogenesis of the chronic disease forms, chronic inflammatory demyelinating peripheral neuropathy and multifocal motor neuropathy are less well-known. Immunomodulatory treatments with corticosteroid or cytotoxic drug treatments, infusion of Ig or therapeutic plasma exchanges are variably effective. The article outlines the principles and practices of an individualized approach to therapy.