Imaging and cytological analysis of 92 patients with Japanese encephalitis

Aim: Japanese encephalitis (JE) is caused by a mosquito-borne flavivirus and demonstrates high mortality and serious sequelae. Imaging and cytological examinations are important for the diagnosis of JE. We performed this study to analyze the imaging and cytological characteristics of JE.Methods: This study enrolled 92 JE patients with 108 cerebral spinal fluid (CSF) samples. Diagnosis was based on clinical features and positive immunoglobulin M antibodies against JE virus, which were measured using enzyme-linked immunosorbent assay. All patients received detailed neurological examinations, relevant cerebrospinal fluid tests, and brain neuroimaging (computed tomography, magnetic resonance imaging, or both).Results: Prominent involvement in the hippocampus was observed in 10 patients on neuroimaging, in addition to classic involvement in the thalamus and basal ganglia. Lumbar puncture pressure was normal in 61 CSF samples. White cell count increased in 81.19% of CSF samples, 67.65% and 83.33% of CSF samples demonstrated normal chloride and glucose concentrations, respectively, and 82.52% of CSF samples demonstrated > 0.4 g/L protein content. JE patients demonstrate mixed-cell reaction on cerebrospinal fluid cytology in the early phase, which subsequently mainly develop as mainly lymphocyte reaction or typical lymphocyte reaction.Conclusion: JE imaging is characterized by bilateral thalamic involvement, and the basal ganglia and hippocampus are also commonly affected. The mixed-cell reaction in JE lasts longer than in general viral encephalitis. This may facilitate the differential diagnosis of JE