Understanding Guillain-Barré Syndrome
Understanding Guillain-Barré Syndrome
abstract & commentary
Source: Kuwabara S, et al. IgG anti-GM1 antibody is associated with reversible conduction failure and axonal degeneration in Guillain-Barré syndrome. Ann Neurol 1998;44: 202-208.
Among 34 consecutive guillain-barré syndrome (GBS) patients seen between 1992-1996, 16 were serologically IgG anti-GM1 positive and electrodiagnostically either acute motor axonal neuropathy (AMAN, n = 11), acute motor and sensory axonal neuropathy (AMSAN, n = 1), acute inflammatory demyelinating polyneuropathy (AIDP, n = 3), or indeterminate (n = 1). Eighteen were antibody negative. Proportionately more antibody positive, compared to antibody negative, patients had a poor outcome (inability to stand at 6 months) but, surprisingly, six (4 AMAN, 1 each AIDP, or indeterminate) demonstrated rapid clinical improvement. Electrophysiologic improvement of conduction block and velocity slowing, without temporal dispersion or polyphasia, was unusually rapid among six antibody positive cases (three each with AMAN and AIDP), suggesting that reversal of conduction failure at the node of Ranvier, rather than demyelination and remyelination, was critical to improvement. Immune mediated axonal degeneration and reversible conduction failure are the underlying pathophysiologic mechanisms in IgG anti-GM1 positive GBS.
Commentary
C. jejuni isolates from seven GBS patients (5 AMAN, 1 AIDP, 1 Fisher syndrome) were compared with strains of C. jejuni isolated from 11 patients with sporadic diarrhea, to determine whether they differed in their lipopolysaccharide (LPS) content. Although only GBS patients, except for the Fisher syndrome, demonstrated significantly elevated anti-GM1 and anti-GD1a antibody titers in their sera compared to the pure enteritis group, Campylobacter isolated from both groups had similar ganglioside-like moieties, indicating that factors other than C. jejuni determine which enteritis patients develop GBS and which do not (Sheikh K, et al. Neurology 1998;51;371-378).
Host susceptibility may play an important role but findings implicating genetic factors are conflicting. Comparing 81 Japanese GBS patients with 87 controls, Ma et al report no significant difference in the incidence of a variety of genetic markers, including T-cell receptor alpha-chain constant, and beta-chain variable, gene polymorphisms, and HLA class I antigens, HLA-DRB1 and HLA-DQB1, regardless of anti-GM1 antibody positivity, recent C. jejuni infection, or both (Ma JJ, et al. Neurology 1998;51:379-384). However, an association between C. jejuni-associated GBS and HLA-DQB1*03 in British patients, HLA-B35 in Japanese patients, and HLA-DRB1*1301 in Chinese patients provide some evidence for genetic susceptibility (Feasby TE, et al. Neurology 1998;51:340-342). Molecular mimicry between C. jejuni and a neural epitope, in the presence of a genetically susceptible person, appears to be a plausible explanation for GBS following Campylobacter enteritis. The precise host susceptibility factor remains a mystery.
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