Pediatric Herpes Simplex Virus-1 Encephalitis

  • Etiology: necrotizing hemorrhagic encephalitis, localized in limbic system
  • Imaging: bilateral + asymmetric temporal encephalitis – affects mesial temporal lobes early, can enhance
  • CT: normal or diffuse mild edema / swelling
  • MRI: diffuse, T2 hyperintense, especially in gray matter, variable contrast enhancement
  • Clinical: in older child / adult

Radiology Cases of Herpes Simplex Virus-1 Encephalitis

US of HSV-1 / herpes simplex virus-1 encephaliti
Coronal US of the brain (above) shows a round echogenic lesion in the left fronto-parietal region. Axial CT without contrast of the brain (below) shows the lesion to be high density with surrounding low density edema and felt to represent intraparenchymal hemorrhage.