Type:
Educational Exhibit
Keywords:
Not applicable, Infection, Imaging sequences, MR-Diffusion/Perfusion, MR, Paediatric, Neuroradiology brain, CNS, Neuro
Authors:
J. Rajasekaran, K. Gopinathan, P. D. J. Devimeenal, D. K. GEETHA, S. Nagarajan; Chennai/IN
DOI:
10.26044/ecr2020/C-11147
Background
Infectious diseases continue to be a major cause of mortality and morbidity in developing countries despite our efforts to control them. Among the infectious agents, viruses remain the most common cause of CNS infection, particularly in paediatric population.
Fig. 2: Viral encephalitis - common causes
References: Dept. of radiology, Government kilpauk medical college, Chennai/IN
Viruses are obligate intracellular pathogens which gain access to the CNS through hematogenous (e.g. arbovirus), neurogenic (e.g. rabies, herpes virus) and respiratory (e.g. influenza) routes.
Most cases of viral encephalitis are managed by symptomatic treatment and prompt supportive care. But antiviral therapy can be lifesaving in certain infections and hence early and prompt diagnosis is of vital importance.
The clinical presentation and radiological features of viral encephalitis are nonspecific. The single most valuable investigation in establishing a specific diagnosis is CSF analysis to identify virus specific antibodies (IgM/IgG) or viral DNA/RNA (using PCR).
But factors like false negative CSF PCR results either due to sampling too early/ too late or after institution of antiviral agents, availability of these investigations; and lag time in getting the results complicate the clinical decision making. Neuroimaging is crucial in such cases which aids in diagnosing the aetiology, identifies complications and helps in prognostication. In this article, we try to bring out the differences in the MR imaging features of few common viral encephalitis. Wherever possible, the specific imaging features are highlighted with proper reasoning.
Fig. 3: Common sites of predilection
References: Dept. of radiology, Government kilpauk medical college, Chennai/IN
Fig. 4: Common sites of predilection
References: Dept. of radiology, Government kilpauk medical college, Chennai/IN