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| __NOTOC__
| | #REDIRECT [[Varicella zoster encephalitis]] |
| {{CMG}} {{AE}} {{AG}}
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| {{SK}} Varicella zoster virus encephalitis; Herpes zoster encephalitis; Varicella zoster encephalitis; Varicella encephalitis;
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| ==Overview==
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| VZV encephalitis is a viral infection of the [[central nervous system]]. Based on the duration of symptoms, VZV encephalitis may be classified into either acute or chronic. The exact pathogenesis of VZV encephalitis is not fully understood. The [[immune system]] eliminates the virus from most locations upon initial infection, but it remains [[viral latency|latent]] in the [[dorsal root ganglion]] and the [[trigeminal]] ganglion near the base of the skull. VZV encephalitis may be caused by either varicella ([[chickenpox]]) or herpes zoster ([[shingles]]). VZV encephalitis must be differentiated from other diseases that cause [[fever]], [[headache]], [[vomiting]], and [[altered mental status]]. The incidence of VZV encephalitis is approximately 10 per 100,000 individuals affected with [[varicella]], most often [[neonates]] and the elderly.<ref name="pmid7658062">{{cite journal| author=Choo PW, Donahue JG, Manson JE, Platt R| title=The epidemiology of varicella and its complications. | journal=J Infect Dis | year= 1995 | volume= 172 | issue= 3 | pages= 706-12 | pmid=7658062 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7658062 }} </ref> If left untreated, [[immunocompromised]] patients with VZV encephalitis may progress to [[mortality]]. Common complications include [[shock]], [[hypoxemia]], and [[meningitis]]. Signs of VZV encephalitis include [[fever]], [[headache]], [[ataxia]], and [[aphasia]]. Laboratory findings consistent with the diagnosis of VZV encephalitis include [[leukocytosis]] and [[pleocytosis]].<ref name=Mandell1> M.D. JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Expert Consult Premium Edition. Saunders; 2014.</ref> [[Magnetic resonance imaging]] is the imaging modality of choice for VZV encephalitis. [[Acyclovir]] is the drug of choice to treat VZV encephalitis.
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| ==Classification==
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| Based on the duration of symptoms, VZV encephalitis may be classified into either acute or chronic.
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| ==Pathophysiology==
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| 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.<ref name=Mandell1> M.D. JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Expert Consult Premium Edition. Saunders; 2014.</ref> The [[immune system]] eliminates the virus from most locations upon initial infection, but it remains [[viral latency|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 cell]]s.<ref name="pmid9300702">{{cite journal| author=Sadzot-Delvaux C, Kinchington PR, Debrus S, Rentier B, Arvin AM| title=Recognition of the latency-associated immediate early protein IE63 of varicella-zoster virus by human memory T lymphocytes. | journal=J Immunol | year= 1997 | volume= 159 | issue= 6 | pages= 2802-6 | pmid=9300702 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9300702 }} </ref> The molecular basis of reactivation remains unknown.<ref name=Mandell1> M.D. JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Expert Consult Premium Edition. Saunders; 2014.</ref> Some histopathologic studies suggest of a postinfectious [[demyelinating]] process, while other findings cite direct viral cytopathology.<ref name="pmid6326714">{{cite journal| author=Bauman ML, Bergman I| title=Postvaricella encephalitis. | journal=Arch Neurol | year= 1984 | volume= 41 | issue= 5 | pages= 556-8 | pmid=6326714 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=6326714 }} </ref><ref name="pmid4311227">{{cite journal| author=McCormick WF, Rodnitzky RL, Schochet SS, McKee AP| title=Varicella-Zoster encephalomyelitis. A morphologic and virologic study. | journal=Arch Neurol | year= 1969 | volume= 21 | issue= 6 | pages= 559-70 | pmid=4311227 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=4311227 }} </ref><ref name="pmid582251">{{cite journal| author=Takashima S, Becker LE| title=Neuropathology of fatal varicella. | journal=Arch Pathol Lab Med | year= 1979 | volume= 103 | issue= 5 | pages= 209-13 | pmid=582251 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=582251 }} </ref>
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| ==Causes==
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| VZV encephalitis may be caused by either varicella ([[chickenpox]]) or herpes zoster ([[shingles]]).
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| ==Differentiating VZV Encephalitis from Other Diseases==
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| VZV encephalitis must be differentiated from other diseases that cause [[fever]], [[headache]], [[vomiting]], and [[altered mental status]], such as:<ref name="pmid14978145">{{cite journal| author=Kennedy PG| title=Viral encephalitis: causes, differential diagnosis, and management. | journal=J Neurol Neurosurg Psychiatry | year= 2004 | volume= 75 Suppl 1 | issue= | pages= i10-5 | pmid=14978145 | doi= | pmc=PMC1765650 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14978145 }} </ref><ref name="pmid12353193">{{cite journal| author=Gnann JW| title=Varicella-zoster virus: atypical presentations and unusual complications. | journal=J Infect Dis | year= 2002 | volume= 186 Suppl 1 | issue= | pages= S91-8 | pmid=12353193 | doi=10.1086/342963 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12353193 }} </ref><ref name="pmid13065322">{{cite journal| author=APPELBAUM E, RACHELSON MH, DOLGOPOL VB| title=Varicella encephalitis. | journal=Am J Med | year= 1953 | volume= 15 | issue= 2 | pages= 223-30 | pmid=13065322 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=13065322 }} </ref>
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| {| style="border: 0px; font-size: 90%; margin: 3px;" align=center
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| ! style="background: #4479BA; width: 120px;" | {{fontcolor|#FFF|Disease}}
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| ! style="background: #4479BA; width: 550px;" | {{fontcolor|#FFF|Findings}}
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| | style="padding: 5px 5px; background: #DCDCDC;" | '''Other [[Viral encephalitis]] '''
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| | style="padding: 5px 5px; background: #F5F5F5;" | 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]]. {{see also|Herpes simplex encephalitis|West Nile encephalitis|St. Louis encephalitis|Japanese encephalitis}}
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| | style="padding: 5px 5px; background: #DCDCDC;" | '''[[Bacterial encephalitis]]'''
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| | style="padding: 5px 5px; background: #F5F5F5;" | 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]]. {{see also|Tick-borne encephalitis}}
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| | style="padding: 5px 5px; background: #DCDCDC;" | '''[[Encephalopathy]]'''
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| | style="padding: 5px 5px; background: #F5F5F5;" | Presents with steady [[depression]], generalized [[seizures]]. Generally absent are [[fever]], [[headache]], [[leukocytosis]], and [[pleocytosis]]; [[MRI]] often appears normal.
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| | style="padding: 5px 5px; background: #DCDCDC;" | '''[[Meningitis]]'''
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| | style="padding: 5px 5px; background: #F5F5F5;" |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]]. {{see also|bacterial meningitis|viral meningitis|fungal meningitis}}
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| | style="padding: 5px 5px; background: #DCDCDC;" |'''[[Brain abscess]]'''
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| | style="padding: 5px 5px; background: #F5F5F5;" |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 [[neurosurgery|neurological procedures]].
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| | style="padding: 5px 5px; background: #DCDCDC;" | '''[[Acute disseminated encephalomyelitis]]'''
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| | style="padding: 5px 5px; background: #F5F5F5;" | Presents with scattered foci of [[demyelination]] and perivenular [[inflammation]]; it can cause focal neurological signs and decreased ability to focus.
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| |}
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| ==Epidemiology and Demographics==
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| ===Incidence===
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| The incidence of VZV encephalitis is approximately 10 per 100,000 individuals affected with [[varicella]].<ref name="pmid7658062">{{cite journal| author=Choo PW, Donahue JG, Manson JE, Platt R| title=The epidemiology of varicella and its complications. | journal=J Infect Dis | year= 1995 | volume= 172 | issue= 3 | pages= 706-12 | pmid=7658062 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7658062 }} </ref>
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| ===Age===
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| VZV encephalitis most commonly affects infants or the elderly.<ref name="pmid7658062">{{cite journal| author=Choo PW, Donahue JG, Manson JE, Platt R| title=The epidemiology of varicella and its complications. | journal=J Infect Dis | year= 1995 | volume= 172 | issue= 3 | pages= 706-12 | pmid=7658062 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7658062 }} </ref>
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| ===Gender===
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| Men and women are affected equally by VZV encephalitis.
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| ==Risk Factors==
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| Common risk factors in the development of VZV encephalitis include:<ref name="Mounsey">{{cite journal|title=Herpes zoster and postherpetic neuralgia: prevention and management|author=Mounsey AL, Matthew LG, & Slawson DC|date=2005|journal=American Family Physician|volume=72|issue=6|pages=1075-1080|pmid=16190505|url=http://www.aafp.org/afp/20050915/1075.html|accessdate=2007-06-15}}</ref><ref>{[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}}</ref><ref name="pmid12353193">{{cite journal| author=Gnann JW| title=Varicella-zoster virus: atypical presentations and unusual complications. | journal=J Infect Dis | year= 2002 | volume= 186 Suppl 1 | issue= | pages= S91-8 | pmid=12353193 | doi=10.1086/342963 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12353193 }} </ref><ref name=IDSAEnceph> 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.</ref>
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| *[[Varicella zoster virus]] infection
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| *[[Immunosuppression]]
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| *[[HIV]] or [[AIDS]]
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| *[[Age]] extremes
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| *[[Stress]]
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| *Long-term use of [[corticosteroid]]s
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| *[[Skin]] [[inflammation]]
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| *[[Pregnancy]]
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| *Living in tropical climate
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| *Working as a [[physician]] or other [[health care provider]]
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| *Absence of [[VZV]] immunization
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| ==Natural History, Complications, and Prognosis==
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| ===Natural History===
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| If left untreated, [[immunocompromised]] patients with VZV encephalitis may progress to [[mortality]].
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| ===Complications===
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| Common complications of VZV encephalitis include:<ref name="pmid14978145">{{cite journal| author=Kennedy PG| title=Viral encephalitis: causes, differential diagnosis, and management. | journal=J Neurol Neurosurg Psychiatry | year= 2004 | volume= 75 Suppl 1 | issue= | pages= i10-5 | pmid=14978145 | doi= | pmc=PMC1765650 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14978145 }} </ref>
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| *[[Shock]]
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| *[[Hypoxemia]]
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| *[[Hypotension]]
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| *[[Aphasia]]
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| *[[Seizures]]
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| *[[Meningitis]]
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| *Loss of [[motor]] skills
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| *[[Coma]]
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| *[[Mortality]]
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| ===Prognosis===
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| Prognosis for VZV encephalitis is poor in [[immunocompromised]] individuals.
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| ==Diagnosis==
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| ===History and Symptoms===
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| If possible, a detailed and thorough history from the patient is necessary. Symptoms of VZV encephalitis include:<ref name="pmid12353193">{{cite journal| author=Gnann JW| title=Varicella-zoster virus: atypical presentations and unusual complications. | journal=J Infect Dis | year= 2002 | volume= 186 Suppl 1 | issue= | pages= S91-8 | pmid=12353193 | doi=10.1086/342963 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12353193 }} </ref>
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| *[[Fever]]
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| *[[Headache]]
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| *[[Ataxia|Loss of body control]]
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| *[[Aphasia|Inability to produce or comprehend language]]
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| *[[Seizure]]s
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| *[[Cough]]
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| *[[Dyspnea|Shortness of breath or labored breathing]]
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| *[[Hemoptysis|Coughing up blood]]
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| *[[Rash]]
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| *[[Lethargy]]
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| ===Physical Examination===
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| Common physical examination findings of VZV encephalitis include:<ref name="pmid12353193">{{cite journal| author=Gnann JW| title=Varicella-zoster virus: atypical presentations and unusual complications. | journal=J Infect Dis | year= 2002 | volume= 186 Suppl 1 | issue= | pages= S91-8 | pmid=12353193 | doi=10.1086/342963 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12353193 }} </ref>
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| *[[Fever]]
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| *[[Aphasia]]
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| *[[Ataxia]]
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| *[[Nuchal rigidity]]
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| *[[Nystagmus]]
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| *[[Hypertonia]] or [[hypotonia]]
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| *[[Hyperreflexia]] or [[hyporeflexia]]
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| *Positive [[plantar reflex]]es
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| *[[Hemiparesis]]
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| If [[rash]] and [[ataxia]] are present simultaneously, the clinical presentation is sufficient to establish a diagnosis.
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| ===Laboratory Findings===
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| Rapid diagnostic methods, which include [[polymerase chain reaction]] (PCR) and [[direct fluorescent antibody]] (DFA) assay, are the methods of choice. Polymerase chain reaction testing, the most sensitive test for VZV, can be used for detecting invasive disease, and detects VZV in vesicle fluid, serum, spinal fluid, and other tissues. Direct fluorescent antibody assay is performed on scrapings taken from the base of a skin lesion, and is a rapid and reliable method for diagnosing VZV disease.<ref name="pmid20070670">{{cite journal| author=Pergam SA, Limaye AP, AST Infectious Diseases Community of Practice| title=Varicella zoster virus (VZV) in solid organ transplant recipients. | journal=Am J Transplant | year= 2009 | volume= 9 Suppl 4 | issue= | pages= S108-15 | pmid=20070670 | doi=10.1111/j.1600-6143.2009.02901.x | pmc=PMC2919834 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20070670 }} </ref> Cerebrospinal fluid analysis is essential (unless contraindicated) in all patients with encephalitis.<ref name=IDSAEnceph> 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.</ref> Therefore, [[lumbar puncture]] is warranted. Laboratory findings consistent with the diagnosis of VZV encephalitis include [[leukocytosis]] and [[pleocytosis]].<ref name=Mandell1> M.D. JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Expert Consult Premium Edition. Saunders; 2014.</ref>
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| ===CT===
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| [[Computed tomography]] may be helpful in the diagnosis of VZV encephalitis. Findings on [[CT]] suggestive of VZV encephalitis include subtle low density within the [[anterior]] and [[medial]] [[temporal lobe]] and the [[insular cortex]].<ref name=RadioHSE> Herpes simplex encephalitis. Radiopaedia.org (2016). http://radiopaedia.org/articles/herpes-simplex-encephalitis Accessed on February 9, 2016. </ref> Subtleties become more apparent over time and may progress to [[hemorrhage]], and may eventually spread to the other [[temporal lobe]] after 7-10 days.<ref name="pmid11853816">{{cite journal |author=Whitley RJ, Gnann JW |title=Viral encephalitis: familiar infections and emerging pathogens |journal=Lancet |volume=359 |issue=9305 |pages=507–13 |year=2002 |pmid=11853816 |doi=}}</ref>
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| ===MRI===
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| [[Magnetic resonance imaging]] is the imaging modality of choice for VZV encephalitis. Findings on [[MRI]] suggestive of VZV encephalitis include:<ref name=RadioHSE> Herpes simplex encephalitis. Radiopaedia.org (2016). http://radiopaedia.org/articles/herpes-simplex-encephalitis Accessed on February 9, 2016. </ref><ref name="pmid18319155">{{cite journal| author=Bulakbasi N, Kocaoglu M| title=Central nervous system infections of herpesvirus family. | journal=Neuroimaging Clin N Am | year= 2008 | volume= 18 | issue= 1 | pages= 53-84; viii | pmid=18319155 | doi=10.1016/j.nic.2007.12.001 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18319155 }} </ref>
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| *T1
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| **General [[edema]] in the affected region
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| **Hyperintense signal if complicated by subacute [[hemorrhage]]
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| *T1 C+ (Gd)
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| **Early, enhancement is generally absent
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| **Later, enhancement is variable and may appear as:
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| ***Gyral enhancement
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| ***[[Leptomeningeal]] enhancement
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| ***Ring enhancement
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| ***Diffuse enhancement
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| *T2
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| **Hyperintensity of affected [[white matter]] and [[cerebral cortex]]
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| *DWI/ADC
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| **More sensitive than T2 weighted images
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| **Restricted diffusion is common due to [[cytotoxic]] [[edema]]
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| *GE/SWI
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| **May demonstrate blooming if hemorrhagic
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| [[Image:VZV_Encephalitis_MRI_T2.jpeg|VZV Encephalitis MRI T2]]
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| ===Lumbar Puncture===
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| Cerebrospinal fluid analysis is essential (unless contraindicated) in all patients with encephalitis.<ref name=IDSAEnceph> 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.</ref> Therefore, lumbar puncture may be helpful in the diagnosis of VZV encephalitis. Findings on lumbar puncture suggestive of VZV encephalitis include [[pleocytosis]].<ref name=Mandell1> M.D. JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Expert Consult Premium Edition. Saunders; 2014.</ref>
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| ==Treatment==
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| ===Medical Therapy===
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| The mainstay of therapy for VZV encephalitis is [[antiviral]] therapy. [[Acyclovir]] is the drug of choice to treat VZV encephalitis. [[Ganciclovir]] and adjunctive [[coricosteriods]] can be considered as alternatives.<ref name=IDSAEnceph> 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.</ref>
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| ===Prevention===
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| Effective measures for the primary prevention of VZV encephalitis include VZV vaccination with either [[varicella vaccine]] or [[zostavax]].
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| ==References==
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| {{reflist|2}}
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| [[Category:Primary care]]
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| [[Category:Viral diseases]]
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| [[Category:Infectious disease]]
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| [[Category:Neurology]]
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