Multifocal conduction block in peripheral nerve vasculitis.

Peripheral nervous system (PNS) vasculitis and Guillain-Barré syndrome (GBS) are two distinct entities. Although there may be similarities in clinical presentation, the two are rarely confused. PNS vasculitis typically presents as a mononeuritis multiplex, as an overlapping mononeuritis multiplex, or as a distal symmetric sensorimotor polyneuropathy. Electrophysiologic studies are consistent with a primary axonal pathophysiologic process. In contrast, GBS typically presents with variable, mild sensory symptoms followed by symmetric progressive weakness. Early electrophysiologic studies, when abnormal, usually demonstrate findings consistent with demyelination. We describe two cases of PNS vasculitis in which the initial clinical presentation and the presence of multifocal conduction block on electrophysiologic studies led to the incorrect diagnosis of GBS early in the hospital course. Although GBS must always be considered in patients with rapidly progressive weakness, physicians must remain vigilant for alternative diagnoses, as illustrated by our cases.