"Pseudo-conduction block" in vasculitic neuropathy

The predominant electrophysiologic feature of vasculitic mononeuropathy mul tiplex is axonal loss. Electrophysiologic findings interpreted as conductio n block have, however, also been reported to occur in neuropathy secondary to necrotizing vasculitis. We report 3 patients with mononeuropathy multipl ex and biopsy proven vasculitis in whom eight nerves met criteria for condu ction block. In each circumstance, serial study demonstrated conversion of the electrophysiologic findings to those most consistent with severe axonal loss. "Conduction block" in vasculitic mononeuropathy multiplex is seconda ry to focal axonal conduction failure presumably related to infarctive axon al injury. The term conduction block should be used with caution in this di sorder and only if serial studies demonstrate findings consistent with this electrophysiologic diagnosis. (C) 1999 John Wiley & Sons, Inc.