Asymmetric flaccid paralysis: A neuromuscular presentation of West Nile virus infection

Jun Li, Jeffrey A. Loeb, Michael E. Shy, Aashit K. Shah, Alex C. Tselis, William J. Kupski, Richard A. Lewis

Research output: Contribution to journalArticlepeer-review

133 Scopus citations


The neuromuscular aspects of West Nile virus (WNV) infection have not been characterized in detail. We have studied a group of six patients with proven WNV infection. All cases presented with acute, severe, asymmetric, or monolimb weakness, with minimal or no sensory disturbance after a mild flu-like prodrome. Four cases also had facial weakness. Three of our cases had no encephalitic signs or symptoms despite cerebrospinal fluid pleocytosis. Electrophysiological studies showed severe denervation in paralyzed limb muscles, suggesting either motor neuron or multiple ventral nerve root damage. This localization is supported further by the finding of abnormal signal intensity confined to the anterior horns on a lumbar spine magnetic resonance imaging. Muscle biopsies from three patients showed scattered necrotic fibers, implicating mild direct or indirect muscle damage from the WNV infection. In summary, we describe a group of patients with acute segmental flaccid paralysis with minimal or no encephalitic or sensory signs. We have localized the abnormality to either the spinal motor neurons or their ventral nerve roots. It will be important for physicians to consider WNV infection in patients with acute asymmetric paralysis with or without encephalitic symptoms.

Original languageEnglish (US)
Pages (from-to)703-710
Number of pages8
JournalAnnals of Neurology
Issue number6
StatePublished - Jun 1 2003

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


Dive into the research topics of 'Asymmetric flaccid paralysis: A neuromuscular presentation of West Nile virus infection'. Together they form a unique fingerprint.

Cite this