Author(s): Masahiro Nawata
Japanese encephalitis (JE) is a disease caused by the mosquito-borne Japanese encephalitis virus (JEV). It is prevalent in Southeast Asia and East Asia. Diagnosis of JE is generally accomplished by testing of serum or cerebrospinal fluid (CSF) to detect virus-specific antibodies. Magnetic resonance imaging (MRI) is a useful adjunct for the diagnosis. Thalamic invasion is classical findings of MRI. Other areas in the brain may be invaded are midbrain, pons, cerebellum, basal ganglia, cerebral cortex.
Case 1: A 60-year-old man presented with headache and fever. Neurological examination showed consciousness Kernig’s sign. CSF: JEV HI antibodies: X320. (Figure 1) Axial T2-weighted MR image (4 days after onset) shows high intensity area in the left thalamus (arrow) and the left putamen (curved arrow).
Case 2: A 91 year-old woman presented with deteriorated consciousness. CSF: JEV CF antibodies: X32, JEV HI antibodies: X160. (Figure 2) Axial T2-weighted MR image (8 days after onset) shows high intensity area in the bilateral thalamus (arrow).