Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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July 16, 2015
Epstein-Barr Encephalitis
- Clinical Background: Epstein-Barr virus (EBV) accounts for 5% of all encephalitis in children. About 20% of patients with primary EBV infection will have systemic complications, with neurologic involvement seen in about 5%. The clinical outcome varies from complete recovery to death. The pattern of CNS involvement seen on imaging has prognostic value, as prognosis is worse when there is brain stem involvement.
- Clinical Presentation: Seizures, fever, headache, and Alice in Wonderland syndrome
- Key Diagnostic Features:
- CT will show non-specific areas of decreased attenuation, but this finding has a low sensitivity.
- MRI shows bilateral and symmetric increased T2-weighted signal in the caudate nuclei, putamina (as the virus has special tropism for the basal ganglia), and thalami, and may also involve the cortex. Involvement of the white matter, brainstem and splenium is possible, but rare.
- Both increased and reduced ADC values have been reported.
- MRS might show decreased NAA and increased levels of amino acids and myoinositol, but these are nonspecific findings.
- DDx: EBV has a special tropism for the basal nuclei.
- Similar imaging findings are seen mitochondrial encephalopathy and other organic acidurias, but there is a progressive psychomotor development delayed with other neurological deficits.
- Hypoxic and ischemic injuries, carbon monoxide poisoning, or hypoglycemia may mimic EBV encephalitis, but in such cases the white matter is usually also involved, and the ADC map shows negative values (ie, restricted diffusion).
- Deep vein thrombosis involving the superior or inferior stratal veins has also to be included in the differential, as it will be associated with swelling and variable ADC values, but T2* sequences and CE-MRV can rule out this diagnosis.
- Therefore, the clinical history and the onset of symptoms are key in differentiating EBV encephalitis from other potential causes of basal ganglia signal abnormalities.
- Treatment: Corticosteroids, acyclovir, and anticonvulsants