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

Area of Science:

• Neurology
• Radiology
• Infectious Diseases

Background:

• Japanese encephalitis (JE) is a severe flavivirus infection with significant mortality and morbidity.
• Conventional magnetic resonance imaging (MRI) plays a crucial role in diagnosing and understanding neurological infections.

Purpose of the Study:

• To evaluate conventional MRI findings in Japanese encephalitis patients.
• To investigate potential differences in MRI findings between pediatric and adult JE cases.

Main Methods:

• Retrospective analysis of MRI scans from 54 serologically confirmed JE patients.
• Inclusion of neurological examination and cerebrospinal fluid analysis.
• Comparison of MRI findings based on symptom duration (less than vs. more than 15 days) and age group (pediatric vs. adult).

Main Results:

• Abnormal signal alterations were predominantly observed in the bilateral thalami and substantia nigra in most JE patients.
• Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping showed distinct values based on symptom duration (0.563 × 10^-3 mm²/sec for <15 days vs. 1.095 × 10^-3 mm²/sec for >15 days).
• Mean ADC values for pediatric JE (0.907 × 10^-3 mm²/sec) and adult JE (0.982 × 10^-3 mm²/sec) showed no statistically significant difference.

Conclusions:

• Conventional MRI, particularly DWI with ADC mapping, is valuable for assessing the stage of Japanese encephalitis.
• The study found no statistically significant differences in conventional MRI findings between pediatric and adult JE patients.
• Bilateral thalamic and substantia nigra involvement is a common MRI finding in JE.