A Pediatric Radiology Textbook and Pediatric Radiology Digital Library
Pediatric Herpes Simplex Virus-2 Encephalitis
Etiology: Transvaginal infection
Imaging: Appearance based on time of infection — Intrauterine: Encephalomalacia, ventriculomegaly, scattered calcification, microcephaly — Perinatal: Early may be abnormal, underestimates injury — First week – MRI shows edema, multifocal diffusion restriction, with or without hemorrhage — Later parenchymal destruction, encephalomalacia, atrophy, calcification, ventriculomegaly
Neonatal: Variable (no predilection for temporal lobe) — Multifocal white matter, cortical gray matter, basal ganglia — Patchy parenchymal and meningeal enhancement
Imaging Classically: — Affects deep and periventricular structures rather than temporal lobes — Hemorrhagic necrotizing panencephalitis with multicystic encephalomalacia of entire brain (late)
Imaging MRI: — DWI: Cortical restricted diffusion is most sensitive finding
DDX:
Complications:
Treatment:
Clinical: — In neonate Herpes Simplex Virus-2 more common than Herpes Simplex Virus-1 — Associated with microopthalmia and retinal dysplasia
Radiology Cases of Herpes Simplex Virus-2 Encephalitis
Coronal US of the brain (above left) shows increased periventricular echogenicity around the anterior horns of the lateral ventricles with cystic change on the right. Axial CT without contrast of the brain (above right) shows diffuse low density throughout the brain with loss of gray matter white matter differentiation and high density hemorrhage in the posterior horn of the left lateral ventricle and in the right basal ganglia. Coronal (below right) and axial (below left) T2 MRI of the brain show diffuse necrosis developing in the brain, particularly in the frontal lobes. Intraventricular hemorrhage is again noted and the brain appears to be too smooth in appearance for the gestational age.
