University Hospitals Community Consortium Beachwood, Ohio, United States
Case Diagnosis: Acute Flaccid Myelitis Due to Neuroinvasive West Nile Virus
Case Description: 54-year-old male presented with a week of fevers, rash, fatigue, headache, weakness and bilateral leg pain following a camping trip in Canada. His exam was notable for proximal left lower extremity weakness, intact sensation, and hyporeflexia. Nerve conduction study showed no evidence of large fiber demyelinating peripheral neuropathy. Electromyography was not performed due to early presentation of symptoms. Spine MRI with contrast showed T2/STIR hyperintensity in the spinal cord gray matter from T8 to conus. Brain MRI showed T2/FLAIR hyperintensities in bilateral frontal regions. Lumbar puncture revealed lymphocytic pleocytosis. Cerebrospinal fluid (CSF) studies were notable for West Nile Virus IgM antibodies. He was treated with intravenous immunoglobulin (IVIG), steroids, and physical and occupational therapy at an inpatient rehabilitation facility - showing improvement in overall function.
Discussions: West Nile Virus (WNV) is the leading cause of mosquito-borne disease in the United States. Most cases are asymptomatic, however, about 25% will develop flu-like illness, and 1% present with severe neuroinvasive disease. This includes encephalitis, meningitis, and/or Acute Flaccid Myelitis (AFM). AFM is a rare neurologic disorder affecting the spinal cord gray matter following a viral illness. Patients with AFM typically present with all or most of the following: prodromal fever/illness, weakness and decreased muscle tone involving one or more limbs within 1-10 days of symptom onset, decreased or absent reflexes in at least one limb, CSF showing pleocytosis, and gray matter involvement within the spinal cord with or without nerve root enhancement on MRI.
Conclusions: This patient's clinical presentation, labs, and MRI findings are consistent with a diagnosis of Acute Flaccid Myelitis due to West Nile Virus. Early treatment with IVIG, steroids, and inpatient rehabilitation resulted in overall improvement of function. Early diagnosis and treatment are imperative for preserving function in neuroinvasive WNV.
