[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Central nervous system](https://durgical.com/en/general-pathology/areas/cns/) › Herpesvirus encephalitis

# Herpesvirus encephalitis

- Lesion

Herpes simplex type 1 is the most common cause of serious sporadic encephalitis; zoster and CMV attack the nervous system in other ways.

Updated Nov 12, 2026

## Key points

- HSV-1: inferior and medial temporal lobes and orbital frontal gyri; hemorrhagic necrosis, Cowdry type A intranuclear inclusions.
- HSV-2: neonatal encephalitis acquired from the birth canal; in adults it causes recurrent (Mollaret) meningitis.
- Varicella-zoster: latent in dorsal root and cranial ganglia; shingles is painful vesicles in a dermatome; complications are postherpetic neuralgia, vasculopathy with strokes, and encephalitis in the immunosuppressed.
- CMV in utero: periventricular necrosis and calcification, microcephaly, deafness; in AIDS, ventriculoencephalitis and retinitis.
- Early antiviral treatment of HSV encephalitis greatly lowers mortality.

## What it is

Herpesviruses persist in the body for life and can damage the CNS at first infection or on reactivation. HSV-1 causes a hemorrhagic necrotising encephalitis of the temporal and frontal lobes in children and adults. HSV-2 causes generalised encephalitis in newborns infected at birth. Varicella-zoster reactivates in sensory ganglia to cause shingles and can inflame cerebral arteries. CMV damages the developing brain in utero and the periventricular region in people with AIDS.

## Step by step

- HSV-1 infects the mouth in childhood and becomes latent in the trigeminal ganglion.
- Primary infection or reactivation sends the virus along olfactory or trigeminal pathways to the base of the brain.
- Virus multiplies in neurons and glia of the temporal and orbitofrontal cortex.
- Infected cells die; vessels bleed, causing hemorrhagic necrosis.
- Healing leaves cystic temporal lobes with memory loss and epilepsy.

## Herpesviruses and the nervous system

| Virus | Who | Lesion | Inclusion |
| --- | --- | --- | --- |
| [HSV-1](https://durgical.com/en/conditions/viral-encephalitis/) | Children and adults | Hemorrhagic necrosis of temporal and orbitofrontal lobes | Cowdry type A, intranuclear |
| HSV-2 | Newborns; adults with recurrent meningitis | Diffuse encephalitis; aseptic meningitis | Intranuclear |
| [Varicella-zoster](https://durgical.com/en/conditions/herpes-zoster/) | Older or immunosuppressed adults | Ganglionitis, shingles, vasculopathy, encephalitis | Intranuclear in ganglion cells and glia |
| [Cytomegalovirus](https://durgical.com/en/conditions/cytomegalovirus-infection/) | Fetus; adults with AIDS | Periventricular necrosis and calcification; ventriculitis | Large owl-eye nuclear and cytoplasmic inclusions |

## Clinical notes

- HSV encephalitis: fever, confusion, personality change, seizures, aphasia; MRI shows temporal lobe changes and CSF PCR is diagnostic.
- Herpes zoster is common in Latin America in older adults and people with HIV; vaccination lowers its risk.

## Memory aid

HSV-1 burns the temples, HSV-2 the newborn, zoster the ganglion and CMV the walls of the ventricles.

## Test yourself

Think of the answer, then tap the question to see it.

## Which brain regions does HSV-1 encephalitis typically destroy?

The inferior and medial temporal lobes and the orbital gyri of the frontal lobes, with hemorrhagic necrosis.

## Where does varicella-zoster virus remain latent?

In the sensory neurons of dorsal root and cranial nerve ganglia.

## What does congenital CMV do to the developing brain?

It causes periventricular necrosis and calcification, with microcephaly, seizures and sensorineural hearing loss.

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## Connections

## Related 4

- [Viral encephalitis: the shared pattern](https://durgical.com/en/general-pathology/viral-encephalitis-the-shared-pattern/)
- [HIV in the brain and PML](https://durgical.com/en/general-pathology/hiv-in-the-brain-and-pml/)
- [How brain cells react to injury](https://durgical.com/en/general-pathology/how-brain-cells-react-to-injury/)
- [Patterns of necrosis: coagulative, liquefactive, caseous, fat, fibrinoid, gangrenous](https://durgical.com/en/general-pathology/patterns-of-necrosis-coagulative-liquefactive-caseous-fat-fibrinoid-gangrenous/)

## Related conditions 8

- [Viral encephalitis (herpes simplex encephalitis)](https://durgical.com/en/conditions/viral-encephalitis/)
- [Herpes zoster (shingles)](https://durgical.com/en/conditions/herpes-zoster/)
- [Cytomegalovirus infection](https://durgical.com/en/conditions/cytomegalovirus-infection/)
- [Congenital (TORCH) infections: syphilis, toxoplasmosis, CMV and Zika](https://durgical.com/en/conditions/congenital-infections-syphilis-toxoplasmosis-cmv-and-zika/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)
- [Varicella (chickenpox)](https://durgical.com/en/conditions/varicella/)
- [Herpes zoster ophthalmicus](https://durgical.com/en/conditions/herpes-zoster-ophthalmicus/)
- [Autoimmune encephalitis (including anti-NMDA receptor encephalitis)](https://durgical.com/en/conditions/autoimmune-encephalitis/)

## Microorganisms 4

- [Herpes simplex virus 1](https://durgical.com/en/microbiology/herpes-simplex-virus-1/)
- [Herpes simplex virus 2](https://durgical.com/en/microbiology/herpes-simplex-virus-2/)
- [Varicella-zoster virus](https://durgical.com/en/microbiology/varicella-zoster-virus/)
- [Cytomegalovirus](https://durgical.com/en/microbiology/cytomegalovirus/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Encephalitis | MedlinePlus](https://medlineplus.gov/encephalitis.html) (MedlinePlus, US National Library of Medicine, 2026); [Herpes Zoster](https://www.ncbi.nlm.nih.gov/books/NBK441824/) (StatPearls (NCBI Bookshelf), 2026).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/herpesvirus-encephalitis/