VZV encephalitis
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]
Synonyms and keywords: Varicella zoster virus encephalitis; Herpes zoster encephalitis; Varicella zoster encephalitis; Varicella encephalitis;
Overview
Classification
Based on the duration of symptoms, VZV encephalitis may be classified into either acute or chronic.
Pathophysiology
The exact pathogenesis of VZV encephalitis is not fully understood. It is known that VZV encephalitis is the result of the varicella zoster virus, a double-stranded DNA virus within the Herpesviridae family of viruses.[1] The immune system eliminates the virus from most locations, but it remains latent in the dorsal root ganglion and the trigeminal ganglion near the base of the skull. Initial infection by VZV presents as chickenpox, often in children between 1-9. VZV reactivation, which presents as shingles in adults, is the result of a decline in the frequency of VZV-specific T cells.[2] The molecular basis of reactivation remains unknown.[1] Some histopathologic studies suggest of a postinfectious demyelinating process, while other findings cite direct viral cytopathology.[3][4][5]
Causes
VZV encephalitis may be caused by either varicella (chickenpox) or herpes zoster (shingles).
Differentiating VZV Encephalitis from Other Diseases
VZV encephalitis must be differentiated from other diseases that cause fever, headache, vomiting, and altered mental status, such as:[6][7][8]
| Disease | Findings |
|---|---|
| Other Viral encephalitis | Presents with acute inflammation of the brain, caused by a viral infection; it may complicate into severe brain damage as the inflamed brain pushes against the skull, potentially leading to mortality. |
| Bacterial encephalitis | Presents with acute inflammation of the brain, caused by a bacterial infection; it may complicate into severe brain damage as the inflamed brain pushes against the skull, potentially leading to mortality. |
| Encephalopathy | Presents with steady depression, generalized seizures. Generally absent are fever, headache, leukocytosis, and pleocytosis; MRI often appears normal. |
| Meningitis | Presents with headache, altered mental status, and inflammation of the meninges, which may develop in the setting of an infection, physical injury, cancer, or certain drugs; it may have an indolent evolution, resolving on its own, or may present as an rapidly evolving inflammation, causing neurologic damage and possible mortality. |
| Brain abscess | Presents with an abscess in the brain caused by the inflammation and accumulation of infected material from local or remote infectious areas of the body; the infectious agent may also be introduced as a result of head trauma or neurological procedures. |
| Acute disseminated encephalomyelitis | Presents with scattered foci of demyelination and perivenular inflammation; it can cause focal neurological signs and decreased ability to focus. |
Epidemiology and Demographics
Incidence
The incidence of VZV encephalitis is approximately 10 per 100,000 individuals affected with varicella.[9]
Age
VZV encephalitis most commonly affects infants or the elderly.[9]
Gender
Men and women are affected equally by VZV encephalitis.
Risk Factors
Common risk factors in the development of VZV encephalitis include:[10][11][7][12]
- Varicella zoster virus infection
- Immunosuppression
- HIV or AIDS]
- Age extremes
- Stress
- Long-term use of coritcosteriods
- Skin inflammation
- Pregnancy
- Living in tropical climate
- Working as a physician or other health care provider
Natural History, Complications, and Prognosis
Natural History
If left untreated, immunocompromised patients with VZV encephalitis may progress to mortality.
Complications
Common complications of VZV encephalitis include:[6]
- Shock
- Hypoxemia
- Hypotension
- Aphasia
- Seizures
- Meningitis
- Loss of motor skills
- Coma
- Mortality
Prognosis
Prognosis for VZV encephalitis is poor in immunocompromised individuals.
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
CT
MRI
Treatment
Medical Therapy
Prevention
References
- ↑ 1.0 1.1 M.D. JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Expert Consult Premium Edition. Saunders; 2014.
- ↑ Sadzot-Delvaux C, Kinchington PR, Debrus S, Rentier B, Arvin AM (1997). "Recognition of the latency-associated immediate early protein IE63 of varicella-zoster virus by human memory T lymphocytes". J Immunol. 159 (6): 2802–6. PMID 9300702.
- ↑ Bauman ML, Bergman I (1984). "Postvaricella encephalitis". Arch Neurol. 41 (5): 556–8. PMID 6326714.
- ↑ McCormick WF, Rodnitzky RL, Schochet SS, McKee AP (1969). "Varicella-Zoster encephalomyelitis. A morphologic and virologic study". Arch Neurol. 21 (6): 559–70. PMID 4311227.
- ↑ Takashima S, Becker LE (1979). "Neuropathology of fatal varicella". Arch Pathol Lab Med. 103 (5): 209–13. PMID 582251.
- ↑ 6.0 6.1 Kennedy PG (2004). "Viral encephalitis: causes, differential diagnosis, and management". J Neurol Neurosurg Psychiatry. 75 Suppl 1: i10–5. PMC 1765650. PMID 14978145.
- ↑ 7.0 7.1 Gnann JW (2002). "Varicella-zoster virus: atypical presentations and unusual complications". J Infect Dis. 186 Suppl 1: S91–8. doi:10.1086/342963. PMID 12353193.
- ↑ APPELBAUM E, RACHELSON MH, DOLGOPOL VB (1953). "Varicella encephalitis". Am J Med. 15 (2): 223–30. PMID 13065322.
- ↑ 9.0 9.1 Choo PW, Donahue JG, Manson JE, Platt R (1995). "The epidemiology of varicella and its complications". J Infect Dis. 172 (3): 706–12. PMID 7658062.
- ↑ Mounsey AL, Matthew LG, & Slawson DC (2005). "Herpes zoster and postherpetic neuralgia: prevention and management". American Family Physician. 72 (6): 1075–1080. PMID 16190505. Retrieved 2007-06-15.
- ↑ {[cite journal|title=What does epidemiology tell us about risk factors for herpes zoster?|author=Thomas SL, Hall AJ|journal= Lancet Infect Dis.|date=2004|volume=4|issue=1|pages=26-33|pmid= 14720565}}
- ↑ The Management of Encephalitis: Clinical Practice Guidelines by the Infectious Diseases Society of America. http://www.idsociety.org/uploadedFiles/IDSA/Guidelines-Patient_Care/PDF_Library/Encephalitis.pdf Accessed on February 16, 2016.