The acute immune-mediated polyneuropathies are classified under the eponym Guillain-Barré syndrome (GBS), after the authors of early descriptions of the disease. GBS is an acute monophasic paralyzing illness, usually provoked by a preceding infection. GBS occurs world-wide and all age groups are affected.
Historically, the Guillain-Barré syndrome (GBS) was considered a single disorder. It now is recognized as a heterogeneous syndrome with several variant forms. The major forms are acute inflammatory demyelinating polyradiculoneuropathy (AIDP), the Miller Fisher syndrome (MFS), acute motor axonal neuropathy (AMAN), and acute sensorimotor axonal neuropathy (AMSAN). Each form of GBS has distinguishing clinical, pathophysiologic, and pathologic features. (See "Clinical features and diagnosis of Guillain-Barré syndrome in adults".)
The pathogenesis of GBS will be reviewed here. Other aspects of GBS are discussed separately. (See "Clinical features and diagnosis of Guillain-Barré syndrome in adults" and "Treatment and prognosis of Guillain-Barré syndrome in adults".)
One proposed mechanism for Guillain-Barré syndrome (GBS) is that an antecedent infection evokes an immune response, which in turn cross-reacts with peripheral nerve components because of the sharing of cross-reactive epitopes (molecular mimicry) . The end result is an acute polyneuropathy. This immune response can be directed towards the myelin or the axon of peripheral nerve.
Immune reactions directed against epitopes in Schwann cell surface membrane or myelin can cause acute inflammatory demyelinating neuropathy (AIDP) . The pathology is that of multifocal inflammatory demyelination starting at the level of the nerve roots. The earliest changes are frequently seen at the nodes of Ranvier. Both the cellular and humoral immune responses participate in the process. Invasion by activated T-cells is followed by macrophage-mediated demyelination with evidence of complement and immunoglobulin deposition on myelin and Schwann cells [3-5]. No specific myelin antigen(s) have been identified.