Viral encephalitis- sequelae

Case contributed by Dr Mohamed Saber

Presentation

Fever, disturbed conscious level, seizures, history of severe gastroenteritis 1 week ago

Patient Data

Age: 5 years
Gender: Female

Non-enhanced CT study shows the following:

  • multiple variable-sized patchy hypodense lesions are seen involving both cerebral hemispheres cortical and subcortical regions as well as basal ganglia mainly seen at the bifrontal, bilateral parietal as well as right caudate & lentiform nuclei and thalamus
  • effaced supra- tentorial extra-axial CSF spaces due to mass effect
  • normal posterior fossa
  • no hydrocephalus

MRI study shows the following:

  • multiple variable-sized patchy lesions are seen involving both cerebral hemispheres cortical and subcortical regions as well as the basal ganglia mainly seen at the bifrontal, bilateral parietal as well as right caudate & lentiform nuclei and thalamus.
  • the involved regions appear swollen, and elicit signal alteration (low T1/ high T2 and FLAIR) with diffusion restriction in DWI. Gyriform/ leptomeningeal enhancement patterns are seen in the post-contrast study   
  • normal posterior fossa
  • no hydrocephalus

Follow up MRI study shows the following:

  • patchy encephalomalacia and gliosis of the involved regions, elicit CSF-like signal with surrounding T2 & FLAIR hyperintensities. Hyperintensities noted at DWI and ADC are related to T2 shine through artifact
  • cortical laminar necrosis presents as gyriform T1 hyperintensities
  • cerebral atrophy and volume loss present as dilatation of the supratentorial ventricular system and extra-axial CSF spaces

Case Discussion

This case is a good example of how viral encephalitis is occasionally aggressive and destructive of the brain tissue. Within less than one month, encephalomalacia, cortical laminar necrosis, and cerebral atrophy develop with a subsequent permanent disability

Cortical laminar necrosis is usually described in cases of cerebral infarction and metabolic diseases, however, it is also reported in patients with encephalitis 1

In this case, the preceding gastroenteritis and the CSF analysis results were highly suggestive of viral encephalitis.  

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