NEW YORK (Reuters Health) Jul 07 - Acute paralysis is among the symptoms caused by West Nile virus infection, according to a report in the July 8th issue of Neurology.
West Nile virus first emerged in the Western Hemisphere in the summer of 1999, the authors explain, but few reports have detailed the spectrum of disease caused by the virus.
Dr. Lara Jeha and colleagues from The Cleveland Clinic Foundation report on the clinical, electrodiagnostic, radiologic, and pathologic findings in 23 West Nile virus (WNV)-infected patients found to have meningitis, encephalitis, weakness, or any combination thereof.
Twenty-six percent of patients had all three manifestations of WNV infection, the authors report, and 17% had encephalitis and weakness. Only 4% of patients had isolated weakness.
Nine patients, 6 of whom had flaccid quadriparesis, required mechanical ventilation, the report indicates. Three patients died, 2 with meningoencephalitis and flaccid quadriplegia and 1 with isolated encephalitis.
About a quarter of the patients had a nonpruritic, maculopapular, erythematous rash beginning 3 to 7 days before presentation and resolving prior to neurological manifestations, the researchers note.
Electrodiagnostic testing showed reduced motor response amplitudes and normal to absent sensory responses, and needle examination showed active denervation with a more proximal than distal distribution.
Brain CT results were unrevealing, the results indicate, but MRI results were abnormal in one-third of the patients tested. Spinal MRI was also abnormal in over a third of the patients with weakness.
"MRI of the spine is helpful in documenting myelitis as the cause of weakness," Dr. Jeha told Reuters Health, "especially in patients presenting with isolated limb weakness and fever. In such patients, MRI is important to rule out other etiologies for the weakness such as epidural abscesses. Also, at this stage of our knowledge about the disease, it would be helpful to get as much information as we can about its radiologic criteria to see if there is any correlation between disease behavior and prognosis on one hand with presence or absence of MRI abnormalities on the other."
Autopsy results showed perivascular chronic inflammation involving the meninges and parenchymal vessels of the brain, as well as inflammatory and reactive changes in the spinal cord.
"We need to keep an open mind and have a high level of suspicion for new emerging infections causing focal, and sometimes devastating, neurological symptoms," Dr. Jeha concluded. "Researchers should focus on trying to find a vaccine or a cure for this infection that can potentially cause more damage than that caused by polio earlier this century."
Neurology 2003;61:55-59.
