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Neurologic manifestation caused by West Nile virus: A case report

RESUMO

Case presentation: A 39 years old male, physician, traveled to Egypt recently, where he presented odynophagia, myalgia, painful cervical lymphadenopathy, diffuse rash and fever. Symptoms were self-limited for a period of 15 days. Approximately two weeks after the episode, he started feeling burning pain in the scalp, in the left parietal region, associated with dysesthesia. It evolved with pain in the bilateral pectoral region with progression to the back at T4 sensory level, radiating to the thoracoabdominal region on the right to the superior iliac crest and later to the right leg. He denied weakness, mental confusion and dysautonomic symptoms. Cervical ultrasound showed lymph nodes with a reaction pattern. Screening with viral serologies was started and MRI of the spine and brain was performed, which showed areas with hypersignal on T2 in the spinal cord extending from T8 to T11 without anomalous enhancement. CSF was collected with opening pressure of 30cmH2O; 2 cells/m2 lymphocytic predominance; proteins 70mg/dL; ADA 2mg/dL. Positive serum West Nile IgM test. After confirmation of the diagnosis, the patient received 4 days of metriprednisolone 1g/day with satisfactory improvement of symptoms.
Discussion: West Nile fever is caused by the West Nile virus of the flavivirus class and has been one of the major emerging causes of encephalitis in the US. Transmission occurs mainly through the bite of infected Culex mosquitoes, but vertical transmission and blood transfusion have already been described. Although most individuals who contract the virus are asymptomatic, symptoms such as fever, rash and myalgia are part of the clinical apresentation. Neuroinvasion usually occurs in less than 1% of those infected and is characterized by aseptic meningitis, meningoencephalitis, acute flaccid paresis, rhomboencephalitis, myelopathy, polyneuropathy, or radiculopathies. The form of neurological involvement varies according to the seasonality and location of the epidemic. CSF usually shows pleocytosis with a lymphocytic pattern, normal glucose, high protein levels (>900mg%). West Nile virus IgM titers tend to remain high even after acute infection.
Final comments: In Brazil, West Nile Fever is not a common cause of myelopathies, and other diagnoses, such as arboviruses, are primarily considered. In the aforementioned case, the epidemiology retrieved during the anamnesis was essential for the investigation and conclusion of the proper diagnosis.

Palavras Chave

West Nile Virus Infection; Myelitis; Arbovirus Infections