title: Asymmetric Weakness and West Nile Virus Infection.
abstract: BACKGROUND
  Weakness is a common presentation in the emergency department (ED). Asymmetric weakness or weakness that appears not to follow an anatomical pattern is a less common occurrence. Acute flaccid paralysis with no signs of meningoencephalitis is one of the more uncommon presentations of West Nile virus (WNV). Patient may complain of an acute onset of severe weakness, or even paralysis, in one or multiple limbs with no sensory deficits. This weakness is caused by injury to the anterior horn cells of the spinal cord. We present a case of acute asymmetric flaccid paralysis with preserved sensory responses that was eventually diagnosed as neuroinvasive WNV infection.
  
  
  METHODS
  A 31-year-old male with no medical history presented with complaints of left lower and right upper extremity weakness. Computed tomography scan was negative and multiple other studies were performed in the ED. Eventually, he was admitted to the hospital and was found to have decreased motor amplitudes, severely reduced motor neuron recruitment, and denervation on electrodiagnostic study. Cerebrospinal fluid specimen tested positive for WNV immunoglobulin (Ig) G and IgM antibodies. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Acute asymmetric flaccid paralysis with no signs of viremia or meningoencephalitis is an unusual presentation of WNV infection. WNV should be included in the differential for patients with asymmetric weakness, especially in the summer months in areas with large mosquito populations.
authors.affiliation: Department of Medicine, Section of Emergency Medicine, Baylor College of Medicine, Houston, Texas.
authors.forename: Dick C
authors.initials: DC
authors.lastname: Kuo
authors.affiliation: Department of Medicine, Section of Emergency Medicine, Baylor College of Medicine, Houston, Texas.
authors.forename: Saadiyah
authors.initials: S
authors.lastname: Bilal
authors.affiliation: Department of Medicine, Baylor College of Medicine, Houston, Texas.
authors.forename: Paul
authors.initials: P
authors.lastname: Koller
mesh_terms: D000208:Acute Disease; D000328:Adult; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D018908:Muscle Weakness / Q000503:physiopathology* / Q000821:virology*; D014901:West Nile Fever / Q000150:complications*; D014902:West Nile virus / Q000472:pathogenicity
keywords: West Nile virus; asymmetric weakness