Neurological manifestations of West Nile virus infection.
BACKGROUND
Over the past four years, West Nile virus (WNV) has become a significant health issue in North America. In 2002, WNV infection made its first appearance in the human population in Canada.


METHODS
Patients who presented to the University Health Network and Mount Sinai Hospital in Toronto with neurological disease attributed to WNV infection were identified and followed by the neurology service. Clinical features and results of laboratory, electrodiagnostic, radiological and pathological studies are presented.


RESULTS
In August and September 2002, 26 patients were admitted with WNV infection; 14 presented with neurological illness. Encephalitis was the most common presentation (11 patients). Eleven patients developed neuromuscular disease; two at presentation and nine after encephalitis. While the majority had a motor process that localized to the anterior horn cell and/or motor neuron, two patients had evidence of a demyelinating neuropathy and one a sensorimotor axonal neuropathy. Less common manifestations included rhombencephalitis, ataxia, myelopathy and parkinsonism. Death occurred in four patients; two > 75 years of age, and two who were immunocompromised.


CONCLUSIONS
The most common neurological manifestation of WNV infection was encephalitis with subsequent neuromuscular involvement. The diversity of clinical and pathological findings, however, suggests widespread involvement of the central and peripheral nervous system. A poorer prognosis for neurological recovery and overall survival was seen in older and immunocompromised patients.
Burton
Jodie M
JM
University Health Network, University of Toronto Department of Medicine, Division of Neurology, Toronto, Ontario, Canada.
Kern
Ralph Z
RZ
Halliday
William
W
Mikulis
David
D
Brunton
James
J
Fearon
Margaret
M
Pepperell
Caitlin
C
Jaigobin
Cheryl
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada / Q000453:epidemiology; D002493:Central Nervous System Diseases / Q000453:epidemiology* / Q000821:virology; D002524:Cerebellar Ataxia / Q000453:epidemiology / Q000821:virology; D015897:Comorbidity; D018792:Encephalitis, Viral / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008587:Meningitis, Viral / Q000453:epidemiology; D008875:Middle Aged; D009468:Neuromuscular Diseases / Q000453:epidemiology*; D010523:Peripheral Nervous System Diseases / Q000453:epidemiology* / Q000821:virology; D014901:West Nile Fever / Q000453:epidemiology* / Q000401:mortality