title: Imaging findings of neonatal herpes simplex virus type 2 encephalitis.
abstract: BACKGROUND
  The CT, MR, and diffusion-weighted initial and follow-up imaging findings in neonatal herpes simplex virus type 2 (HSV-2) encephalitis were assessed.
  
  
  METHODS
  The clinical, laboratory and imaging findings in 12 patients (eight girls and four boys) with proven neonatal HSV-2 encephalitis with follow-up were retrospectively reviewed. Patterns of brain involvement and distribution of lesions were studied and the contribution of diffusion-weighted imaging to the imaging diagnosis of this disease was explored. A total of 24 CT and 22 MRI studies were performed with a mean follow-up time of 38 months.
  
  
  RESULTS
  Neonatal HSV-2 encephalitis can be multifocal or limited to only the temporal lobes, brainstem, or cerebellum. The deep gray matter structures were involved in 57% of patients, and hemorrhage was seen in more than half of the patients. CT images were normal or showed mild abnormalities in the early stages of the disease. Conventional MR images may be normal in the early stages of the disease. Lesions were initially seen only by diffusion-weighted imaging in 20% of the patients and this modality showed a substantially more extensive disease distribution in an additional 50% of patients. In 40% of patients, watershed distribution ischemic changes were observed in addition to areas of presumed direct herpetic necrosis.
  
  
  CONCLUSIONS
  Neonatal HSV-2 encephalitis has a variable imaging appearance. Diffusion-weighted MRI is an important adjunct in the imaging evaluation of this disease. Watershed distribution ischemia in areas remote from the primary herpetic lesions may be seen.
authors.affiliation: Children's Hospital of Philadelphia, University of Pennsylvania, 34th and Civic Center Blvd., Philadelphia, PA 119104, USA. vossough@email.chop.edu
authors.forename: Arastoo
authors.initials: A
authors.lastname: Vossough
authors.forename: Robert A
authors.initials: RA
authors.lastname: Zimmerman
authors.forename: Larissa T
authors.initials: LT
authors.lastname: Bilaniuk
authors.forename: Erin M
authors.initials: EM
authors.lastname: Schwartz
mesh_terms: D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D020803:Encephalitis, Herpes Simplex / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D018258:Herpesvirus 2, Human; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed