"Bilateral Nigral Hyperintensity Sign" in Epstein-Barr Virus Encephalitis

Epstein-Barr virus (EBV) encephalitis is a rare cause of encephalitis in India and has no pathognomic imaging findings described. Here, we describe the case of a 17-year-old male with fever, cerebellitis, and extrapyramidal involvement, followed by altered sensorium. Imaging showed T2/fluid-attenuated inversion recovery bilaterally symmetric hyperintensities with diffusion restriction in substantia nigra. Cerebrospinal fluid analysis and polymerase chain reaction were positive for EBV. Magnetic resonance imaging findings in EBV encephalitis are known to occur in cortical, subcortical regions, white matter, basal ganglia, thalamus, brain stem, and cerebellum. Isolated involvement of substantia nigra is less reported in the literature. Hence, this case highlights the clinical radiological correlation that can be seen in EBV encephalitis with secondary parkinsonism. The patient recovered after starting antivirals, steroids, and other symptomatic treatments.