In which encephalitis are cerebral infarcts most commonly observed?

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Last updated: October 8, 2026 • View editorial policy

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VZV (Varicella-Zoster Virus) Encephalitis

Cerebral infarcts are most commonly observed in VZV (varicella-zoster virus) encephalitis, where large vessel vasculopathy is the predominant pathological finding in immunocompetent adults. 1

Key Clinical Features

In immunocompetent adults with VZV-related CNS disease, the most common pathological finding is a large vessel vasculopathy that clinically presents as stroke, with ischemic or hemorrhagic infarcts and intracranial arterial abnormalities visible on cranial imaging. 1

Pediatric Considerations

In children, VZV CNS disease manifests similarly:

  • Large vessel vasculitis is the most common pathogenesis in immunocompetent children 2
  • Presents with ischemic or hemorrhagic infarcts visible on MRI and angiography 2
  • VZV infection accounts for up to one-third of arterial strokes in pediatric practice 2
  • Mean presentation time is 3 months after rash (range: 1 week to 48 months), though early manifestations can occur within days 2

Immunocompromised Patients

In immunocompromised children, VZV may cause multifocal leukoencephalopathy that follows a clear arterial distribution 2

Contrast with HSV Encephalitis

While HSV encephalitis is more common overall and typically shows temporal lobe involvement with edema and hemorrhage on MRI, it does not characteristically present with large vessel infarcts. The MRI changes in HSV encephalitis include gyral edema and high signal intensity in the cingulate gyrus and medial temporal lobes, but these represent direct viral cytopathology rather than vascular occlusion 1.

Clinical Pitfalls

  • VZV encephalitis may occur without a zoster rash, fever, or CSF pleocytosis, particularly in reactivation cases in elderly or immunocompromised patients 1
  • The onset can be insidious rather than acute 1
  • Consider VZV testing in any stroke patient with recent or concurrent varicella/zoster infection, even if the rash has resolved

Diagnostic Approach

When cerebral infarcts are identified in suspected encephalitis:

  • Obtain urgent MRI with vascular imaging (MRA or CTA) to identify large vessel abnormalities
  • Test CSF for VZV PCR and VZV IgG/IgM 3
  • Consider VZV serology in serum
  • Start empiric acyclovir if VZV encephalitis is suspected while awaiting confirmatory testing

References

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.