Acute Flaccid Paralysis: The Spectrum of a Newly Recognized Complication of West Nile Virus Infection

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Objectives. Acute flaccid paralysis (AFP) has recently emerged as a major central nervous system complication associated with West Nile virus (WNV) infection. The spectrum of clinical presentations of AFP in WNV infection and its sequelae have not been well-studied. Methods. We describe three patients with AFP due to WNV infection and review the clinical presentations of 56 patients with this complication derived from published studies. Results. Patients with AFP and WNV presented with a spectrum of illness ranging from single extremity paralysis to quadriparalysis with cranial nerve involvement. Patients commonly developed respiratory failure (54%) and bladder dysfunction (22%). While fever was nearly universal (92%), signs of meningismus were less common (17%). Cerebrospinal fluid (CSF) analysis generally revealed a modest pleocytosis, and imaging studies were not diagnositic. Persistent neurologic impairment occurred in all survivors; overall mortality rate was high (22%) and was associated with both the extent of paralysis and advanced age. Conclusion. AFP in the setting of WNV is associated with significant mortality and long-term morbidity.