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HSV Encephalitis
Jack Kuritzky, PGY-2
UNC Internal Medicine
August 31, 2009
HSV Encephalitis: General
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Encephalitis: 20,000 cases/year
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HSV accounts for 10-20%
HSV-1 causes encephalitis in adults
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HSV-1 or HSV-2 in neonates
HSV-1 and 2 associated w/Mollaret’s meningitis
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Preferentially affects temporal lobe
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Benign recurrent lymphocytic meningitis
Can rarely cause recurrent brainstem encephalitis
HSV-2 tends to cause global encephalitis
1/3 cases <20yrs and 1/2 cases >50 yrs
HSV Encephalitis: Pathogenesis
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Infiltrates CNS via 3 routes
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1. Trigeminal nerve or olfactory tract
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2. CNS invasion after recurrent infection
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Viral reactivation w/subsequent spread
3. CNS infection w/o primary or recurrent HSV-1
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Typically after primary infection
<18yrs old
Latent HSV in situ within CNS
Invades and replicates in neurons and glia
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Causes necrotizing encephalitis
Widespread hemorrhagic necrosis throughout parenchyma
HSV Encephalitis: Pathogenesis
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Necrosis of temporal lobe
HSV Encephalitis: Pathogenesis
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Necrosis of temporal lobe
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Immune mediated
Not more common in immunosuppressed
 Small studies suggest HSV viral load does not correlate
with degree of temporal lobe damage
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HSV Encephalitis: Presentation
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Fever
Altered mental status
Altered level of consciousness
Focal cranial nerve deficits
Hemiparesis
Dysphasia/aphasia
Ataxia
Focal seizures
HSV Encephalitis: Presentation
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Fever
Altered mental status
Altered level of consciousness
Focal cranial nerve deficits
Hemiparesis
Dysphasia/aphasia
Ataxia
Focal seizures
HSV Encephalitis: Presentation
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More on AMS – consequences of temporal lobe
damage
Hypomania - elevated mood, excessive animation,
decreased need for sleep, inflated self-esteem, and
hypersexuality
 Kluver-Bucy syndrome (KBS)
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Initially seen in Rhesus monkeys
 Loss of normal anger and fear responses
 Increased sexual activity
 Amnesia
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HSV Encephalitis: Diagnosis
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CSF
Lymphocytic pleocytosis
 Erythrocytosis (84% of patients)
 Elevated protein
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Low glucose uncommon
CSF PCR now diagnostic test of choice
Quickest, sensitive, and specific
 HSV culture out of favor
 Brain biopsies previously performed
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HSV Encephalitis: Diagnosis
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Imaging
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Temporal lobe injury
HSV Encephalitis: Diagnosis
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Imaging – Temporal lobe injury
Usually unilateral
 May have mass effect
 MRI much more sensitive/specific
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EEG – focal findings in >80% cases
High amplitude slow waves (delta and theta slowing)
 Continuous periodic lateralized epileptiform
discharges in the affected region
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HSV Encephalitis: Treatment
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EARLY TREATMENT IMPERATIVE!
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Acyclovir 10 mg/kg IV Q 8h (infuse slowly to prevent
crystalluria/renal failure)
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Before loss of consciousness
Within 24 hours of the onset of symptoms
Glasgow Coma Scale score of 9 to 15
Mortality 19-28% vs. 50-58% w/vidarabine
6 month functional status significantly better w/acyclovir
Treat 14-21 days
Future treatment  steroids? (non-randomized,
retrospective study)
HSV Encephalitis: Prognosis
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Untreated, mortality 70%
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Survivors with severe neurologic damage
With treatment—mortality ~20%!
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Severe disability in 20%
Simplified Acute Physiology Score II >/=27
 Delay >2 days b/w admission and acyclovir
 GCS <6
 Age>30
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62% of survivors have neurologic sequelae
REFERENCES
Kimberline, DW. Management of HSV Encephalitis in Adults and Neonates:
Diagnosis, Prognosis, and treatment. Herpes. (14)1. 2007.
Klein, R. “Clinical manifestations and diagnosis of herpes simplex virus type 1
infection”. UpToDate, version 17.2. Jan 2009.
Klein, R. “Herpes Simplex Type 1 Encephalitis”. UpToDate, version 17.2. Feb
2009.
Shandera, WX and H Koo. “Infectious Diseases: Viral & Rickettsial”. 2007
Current Medical Diagnosis & Treatment. 46th ed. The McGraw Hill
Companies: USA. 2007.
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