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Viral Encephalitis
Case Detail
| Anatomy: Brain-Spine |
 Heather Borders, MD |
| Diagnostic Category: Infectious-Inflammatory |
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| Created: over 3 years ago |
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| Updated: over 3 years ago |
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| Tags:
PEDS
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| Modality/Study Types:
MRI
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Activities:  PDF  ImageJA |
History
Four year old male with a several day history of neurologic changes and abnormal lumbar puncture compatible with viral encephalitis.
Case Images
Diagnosis
Viral Encephalitis
Findings
Diffuse cortical edema and sulcal effacement. Focal edema within the basal ganglia, left thalamus and pons.
No white matter signal alteration was identified.
No abnormal contrast enhancement or restricted diffusion.
Discussion
Encephalitis refers to an acute, usually diffuse, inflammatory process affecting the brain. An infection by a virus is the most common and important cause of encephalitis, although other organisms may sometimes cause an encephalitis.
MRI imaging findings include edema in the affected brain parenchyma with possible diffusion restriction in the acute phase due to cytotoxic edema. Depending on the virus, gray matter, white matter or both may be involved. Also, depending on the virus a particular location may be involved, such as the temporal lobe in HSV.
Other etiologies for encephalitis include; Anoxic/ischaemic, Metabolic, Nutritional deficiency, Toxic,
Systemic infections, Critical illness, Malignant hypertension, Paraneoplastic, Epileptic (non-convulsive status).
ADEM is an important differential consideration. This tends to involve the white matter and is generally asymmetric. In this case, the white matter was not involved and the distribution was symmetric.
The distribution of abnormality did not follow a vascular distribution to suggest ischemia in this case.
In this case, the etiology was not identified; as is the case approximately 50% of the time. The patient continued to improve and was discharged several days after the MRI. The patient was treated with steroids.
Reference
J Neurol Neurosurg Psychiatry 2004;75:i10-i15 doi:10.1136/jnnp.2003.034280
Barkovich: Pediatric Neuroimaging. Viral infections.