Acute motor conduction block neuropathy Another Guillain-Barré syndrome variant.

OBJECTIVE: To report two patients with an acute exclusively motor neuropathy with conduction blocks. METHODS: Serial electrophysiologic studies were carried out. RESULTS: Two patients developed symmetric proximal and distal weakness without sensory abnormalities after enteritis. Tendon reflexes were normal in one patient and brisk in the other. One patient had high titer immunoglobulin G to GD1a and GM1, and the other to GD1b, GD1a, and GM1 and a recent Campylobacter jejuni infection. Electrophysiology showed early partial motor conduction block in intermediate and distal nerve segments, normal sensory conductions even across the sites of conduction block, and normal somatosensory evoked potentials. Conduction blocks resolved in 2 to 5 weeks without excessive temporal dispersion of proximal motor responses. CONCLUSIONS: Acute motor neuropathy with normal or brisk tendon reflexes, conduction block, and fast recovery appears to be a variant of Guillain-Barré syndrome. Conduction block may result from immune-mediated conduction failure at the nodes of Ranvier without demyelination.