Magnetic Resonance Imaging In Human Rabies Encephalitis (1996–2025): A Comprehensive Qualitative And Quantitative Review Of Neuroimaging Patterns And Diagnostic Implications
Keywords:
Rabies encephalitis, MRI findings, grey matter hyperintensity, brainstem involvement, paralytic rabiesAbstract
Background: Rabies encephalitis, caused by Lyssavirus, is a nearly 100% fatal zoonotic disease responsible for ~59,000 deaths annually, mainly in Asia and Africa. It is transmitted through animal bites and presents as furious (~80%) or paralytic (~20%) forms. Diagnosis relies on clinical history and laboratory confirmation (antigen detection, PCR). MRI aids early diagnosis, especially in paralytic cases mimicking Guillain-Barré syndrome or acute disseminated encephalomyelitis. Imaging data are limited, with mostly qualitative reports since the 1990s.
Objective: To qualitatively describe MRI findings in human rabies encephalitis and quantitatively assess the frequency and distribution of abnormalities across reported cases.
Methods: Twenty-two documents (1996–2025) were analysed, including case reports, series, and reviews of confirmed human rabies with MRI findings. Qualitative synthesis categorised abnormalities by brain/spinal regions and disease stages. Quantitative analysis from 12 studies (~120 cases) calculated pooled frequencies of T2/FLAIR hyperintensities, enhancement, and diffusion restriction.
Results: MRI shows non-enhancing T2/FLAIR hyperintensities in grey matter, evolving from subtle to widespread changes. Common sites include brainstem (75–90%), basal ganglia (65–85%), thalami (60–75%), hypothalamus/hippocampus (50–65%), and spinal cord (40–55%). Diffusion restriction occurs in 25–35% of acute cases, while gadolinium enhancement appears in 15–25% of comatose stages. MRI is abnormal in 60–80% of cases but may be normal early.
Conclusions: MRI demonstrates characteristic grey matter involvement, aiding early diagnosis and differentiation from other encephalitides despite possible normal early scans.
Downloads
References
1. SK, Satishchandra P. MRI in a pediatric patient with survival from rabies encephalitis. Int J Infect Dis. 2015;36:24–27.
2. Chaitra TR, Mahadevan A, Kumar S, Shankar SK, Satishchandra P. Rabies encephalitis in a preschool child following postexposure prophylaxis. PLoS Negl Trop Dis. 2015;9(5):e0009045.
3. Mani J, Madhusudanan M, Reddy KC, Mani RS, Satishchandra P, Shankar SK. Neuroimaging of viral infections in the central nervous system. Neuroimaging Clin N Am. 2007;17(1):121–142.
4. Aggarwal A, Aggarwal S, Kini A. Rabies encephalitis: A case report. Radiol Case Rep. 2024;19(11):5116–5120.
5. Chahbi Y, El Kaddoumi M, El Fatimi A. MRI findings in human rabies: A case report on the importance of neuroimaging when biological tests are inconclusive. Radiol Case Rep. 2025;20(8):3246–3250.
6. Solomon T, Hart IJ, Beeching NJ. Viral encephalitis: A review of diagnostic methods and guidelines for management. Neurol India. 2005;53(2):159–166.
7. Karande S, Muranjan M, Mani RS, Mahadevan A, Satishchandra P. An unusual case of rabies encephalitis. Pediatr Infect Dis J. 2015;34(7):772–774.
8. Willoughby RE, Rupprecht CE, Jackson AC. Rabies: Rare human infection. Common questions. Infect Dis Clin North Am. 2007;21(3):649–664.
9. Jackson AC. Rabies virus. In: Encyclopedia of Neuroscience. Elsevier; 2011. p.199–209.
10. Maschke M, Kastrup O, Diener HC. Update on neuroimaging in infectious central nervous system disease. Curr Opin Neurol. 2004;17(4):475–480
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Bibin Joseph, Santoshi Maruti, Deepthi Devadas, Pratheeksha Kamath (Author)
This work is licensed under a Creative Commons Attribution 4.0 International License.
