Reversible proximal conduction block underlies rapid recovery in Guillain-Barré syndrome.

Three patients with Guillain-Barré syndrome underwent electrophysiological examination prior to and during a period of rapid clinical recovery. In each case, improved strength of the abductor digiti minimi coincided with electrophysiologic evidence of a marked reversal of proximal conduction block. In contrast, the degree of distal conduction block remained relatively unchanged after stimulation at the wrist, elbow, axilla, and Erb's point. These findings indicate that rapid motor recovery, early in the course of Guillain-Barré syndrome, can result from reversal of proximal conduction block and explains the often noted dissociation between clinical improvement and conventional distal nerve conduction studies.