IGG ANTI-GM1 ANTIBODY IS ASSOCIATED WITH REVERSIBLE CONDUCTION FAILURE AND AXONAL DEGENERATION IN GUILLAIN-BARRE-SYNDROME

To investigate the pathophysiological role of anti-GM1 antibody in Gui llain-Barre syndrome (GBS), we reviewed sequential nerve conduction st udies of 345 nerves in 34 GBS patients. Statistically significant corr elation between IgG anti-GM1 antibodies and electrodiagnoses was found . Sixteen IgG anti-GM1-positive patients were classified as having acu te motor or acute motor sensory axonal neuropathy (AMAN or AMSAN) (12 patients), as having acute inflammatory demyelinating polyneuropathy ( AIDP) (3 patients), or as undetermined (1 patient) by electrodiagnosti c criteria Besides axonal features, there was rapid resolution of cond uction slowing and block. In 3 patients initially diagnosed as having AIDP, conduction slowing was resolved within days, and 1 of them and 3 AMAN patients showed markedly rapid increases in amplitudes of distal compound muscle action potentials that were not accompanied by prolon ged duration and polyphasia The time courses of conduction abnormaliti es were distinct from those in IgG anti-GM1-negative AIDP patients. Ra pid resolution of conduction slowing and block, and the absence of rem yelinating slow components, suggest that conduction failure may be cau sed by impaired physiological conduction at the nodes of Ranvier. Reve rsible conduction failure as well as axonal degeneration constitutes t he pathophysiological mechanisms in IgG anti-GM1-positive GBS. In both cases, immune-mediated attack probably occurs on the axolemma of moto r fibers.