MRI Spectrum of Japanese Encephalitis in Northeast India: A Cross-Sectional Study.

Japanese encephalitis (JE) is an arthropod-borne flavivirus infection having high mortality and morbidity. This study was performed to evaluate the conventional magnetic resonance imaging (MRI) findings in JE and to find out any difference between pediatric and adult JE.  This retrospective study was performed on serologically positive 54 JE patients presented to a tertiary care hospital with acute encephalitic symptoms between April 2016 and October 2019. Relevant neurological examination, cerebrospinal fluid analysis, and MRI scan of the brain were performed.  Fifty-four JE patients ( = 31 males and = 23 females) having 32 pediatric and 22 adult JE were included in the study sample. Group 1 JE ( = 16) patients had encephalitic symptoms with duration less than 15 days up to the day of MRI scan and group 2 JE ( = 38) had symptoms more than 15 days. Group 1 JE had mean apparent diffusion coefficient (ADC) value of 0.563 ± 0.109 (standard deviation [SD]) × 10 mm /sec and group 2 JE had 1.095 ± 0.206 (SD) × 10 mm /sec. The mean ADC value of pediatric JE was 0.907 ± 0.336 (SD) × 10 mm /sec and adult JE was 0.982 ± 0.253 (SD) × 10 mm /sec.  The majority of the JE patient shows abnormal signal alterations in bilateral thalami and substantia nigra. Diffusion-weighted imaging with ADC mapping helps in evaluating the stage of the JE. No statistical significance of the various conventional MRI findings was found between the pediatric JE and adult JE.