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! style="padding: 0 5px; font-size: 85%; background: #A8A8A8" align=center| {{fontcolor|#2B3B44|Encephalitis Resident Survival Guide Microchapters}}
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align=left | [[Encephalitis resident survival guide#Overview|Overview]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align=left | [[Encephalitis resident survival guide#Causes|Causes]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align=left | [[Encephalitis resident survival guide#Diagnosis|Diagnosis]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align=left | [[Encephalitis resident survival guide#Treatment|Treatment]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align=left | [[Encephalitis resident survival guide#Do's|Do's]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align=left | [[Encephalitis resident survival guide#Don'ts|Don'ts]]
|}
{{CMG}}; {{AE}}[https://www.wikidoc.org/index.php/User:MoisesRomo Moises Romo M.D.]
{{CMG}}; {{AE}}[https://www.wikidoc.org/index.php/User:MoisesRomo Moises Romo M.D.]


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==Overview==
==Overview==
Encephalitis refers to the inflammation of the brain. The causes of encephalitis are mostly infectious, being viruses, bacteria, fungi, or parasites the possible agents. Presentation usually involves headache, fever, confusion, neck stiffness (Kernig and Brudzinski signs), and vomiting. Diagnosis is typically based on clinical presentation and supported by blood tests, medical imaging, and analysis of cerebrospinal fluid. Rapid identification of encephalitis is crucial to reduce sequelae. Management is directed against the affecting agent (antivirals, antibiotics), reducing swelling, and supportive measures.
'''[[Encephalitis]]''' refers to the [[inflammation]] of the [[brain]] parenchyma acompanied of [[neurological]] [[dysfunction]]. The causes of [[encephalitis]] are mostly [[infectious]], being [[viruses]], [[bacteria]], [[fungi]], or [[parasites]] the possible agents. Presentation usually involves [[headache]], [[fever]], [[confusion]], [[neck stiffness]] ([[Kernig]] and [[Brudzinski's Sign|Brudzinski]] signs), and [[vomiting]]. [[Diagnosis]] is typically based on clinical presentation and supported by [[blood tests]], [[medical imaging]], and [[analysis]] of [[cerebrospinal fluid]]. Rapid identification of [[encephalitis]] is crucial to reduce [[sequelae]]. Management is directed against the affecting agent ([[antivirals]], [[antibiotics]]), reducing [[swelling]], and supportive measures.


==Causes==
==Causes==
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Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.
Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.


*All causes of encephalitis may be potentially fatal or disabiling if left untreated in 24 hours.; among them:
*All causes of [[encephalitis]] may be potentially [[fatal]] or disabiling if left untreated in 24 hours; among them:
**Infectious
**[[Infectious]]
***Bacterial
***'''[[Bacterial]]'''
****[[Tuberculosis]]
****[[Tuberculosis]]
****[[Treponema pallidum]]
****[[Treponema pallidum]]
****[[Mycoplasma]]
****[[Mycoplasma]]
***Viral
****[[Listeria monocytogenes]]
****Herpes simplex
****[[Borrelia burgdorferi]]
****Epstein-Barr virus
****[[Brucellosis]]
****Zoster
***'''[[Viral]]'''
****Rabies
****[[Herpes simplex]]
****HIV
****[[Mumps]]
****Cytomegalovirus
****[[Rubella]]
****West Nile virus
****[[Epstein-Barr virus]]
****St. Louis encephalitis virus
****[[Zoster|Varicella zoster]]
****Japanese encephalitis virus
****[[Rabies]]
***Fungal
****[[HIV]]
****Coccidioidomycosis
****[[Cytomegalovirus]]
****Blastomycosis
****[[West Nile virus]]
****Histoplasmosis
****[[St. Louis encephalitis|St. Louis encephalitis virus]]
****Cryptococcosis
****[[Japanese encephalitis virus]]
***Protozoan
***'''[[Fungal]]'''
****Granulomatous amebic
****[[Coccidioidomycosis]]
****Toxoplasma
****[[Blastomycosis]]
****Bartonella Henselae
****[[Histoplasmosis]]
**Autoimmune
****[[Cryptococcosis]]
**Encephalitis lethargica
***'''[[Protozoan]]'''
**Limbic encephalitis
****[[Granulomatous amoebic encephalitis|Granulomatous amebic]]
****[[Toxoplasma]]
****[[Bartonella henselae|Bartonella Henselae]]
**[[Autoimmune]]
**[[Encephalitis lethargica]]
**[[Limbic encephalitis]]


===Common Causes===
===Common Causes===
[[Infectious]]
*[[Herpes simplex]]
*[[Mumps]]
*[[Rubella]]
*[[Epstein-Barr virus]]
*[[Zoster|Varicella zoster]]


==Diagnosis==
==Diagnosis==
Shown below is an algorithm summarizing the diagnosis of encephalitis according to the International Encephalitis Consortium guidelines:
Shown below is an [[algorithm]] summarizing the [[diagnosis]] of [[encephalitis]] according to the International Encephalitis Consortium guidelines:<ref name="VenkatesanTunkel2013">{{cite journal|last1=Venkatesan|first1=A.|last2=Tunkel|first2=A. R.|last3=Bloch|first3=K. C.|last4=Lauring|first4=A. S.|last5=Sejvar|first5=J.|last6=Bitnun|first6=A.|last7=Stahl|first7=J-P.|last8=Mailles|first8=A.|last9=Drebot|first9=M.|last10=Rupprecht|first10=C. E.|last11=Yoder|first11=J.|last12=Cope|first12=J. R.|last13=Wilson|first13=M. R.|last14=Whitley|first14=R. J.|last15=Sullivan|first15=J.|last16=Granerod|first16=J.|last17=Jones|first17=C.|last18=Eastwood|first18=K.|last19=Ward|first19=K. N.|last20=Durrheim|first20=D. N.|last21=Solbrig|first21=M. V.|last22=Guo-Dong|first22=L.|last23=Glaser|first23=C. A.|last24=Sheriff|first24=Heather|last25=Brown|first25=David|last26=Farnon|first26=Eileen|last27=Messenger|first27=Sharon|last28=Paterson|first28=Beverley|last29=Soldatos|first29=Ariane|last30=Roy|first30=Sharon|last31=Visvesvara|first31=Govinda|last32=Beach|first32=Michael|last33=Nasci|first33=Roger|last34=Pertowski|first34=Carol|last35=Schmid|first35=Scott|last36=Rascoe|first36=Lisa|last37=Montgomery|first37=Joel|last38=Tong|first38=Suxiang|last39=Breiman|first39=Robert|last40=Franka|first40=Richard|last41=Keuhnert|first41=Matt|last42=Angulo|first42=Fred|last43=Cherry|first43=James|title=Case Definitions, Diagnostic Algorithms, and Priorities in Encephalitis: Consensus Statement of the International Encephalitis Consortium|journal=Clinical Infectious Diseases|volume=57|issue=8|year=2013|pages=1114–1128|issn=1537-6591|doi=10.1093/cid/cit458}}</ref><br />
<br />


{{Family tree/start}}
{{Family tree/start}}
{{Family tree | | | | | | | | | | | | | | | | | | | | A01 | | | |A01= Patient suspicious for encephalitis}}
{{Family tree | | | | | | | | | | | | | | | | | | | | A01 | | | |A01= Patient suspicious for encephalitis}}
{{Family tree | | | | | | | | | | | | | | | | | | | | |!| | | | | }}
{{Family tree | | | | | | | | | | | | | | | | | | | | |!| | | | | }}
{{Family tree | | | | | | | | | | | | | | | | | | | | B01 | | | | | |B01= PERFORM:<br>• CSF analysis (at least 20 ml): Opening pressure, WBC count with differential, RBC count, protein, glucose, Gram stain and bacterial culture<br>• Routine blood testing<br>• Blood cultures<br>• HSV-1/2 PCR<br>• VZV PCR<br>• Enterovirus PCR<br>• Cryptococcal antigen and/or India Ink staining<br>• Oligoclonal bands and IgG index<br>• VDRL<br>• HIV serology<br>• Hold acute serum and collect convalescent serum 10–14 d later for paired antibody testing<br>• Neuroimaging (MRI preferred to CT, if available)<br>• Chest imaging (Chest x-ray and/or CT)<br>• EEG}}
{{Family tree | | | | | | | | | | | | | | | | | | | | B01 | | | | | |B01= PERFORM:<br>• CSF analysis <br>• Routine blood testing<br>• Blood cultures<br>• HSV-1/2 PCR<br>• VZV PCR<br>• Enterovirus PCR<br>• Cryptococcal antigen and/or India Ink staining<br>• Oligoclonal bands and IgG index<br>• VDRL<br>• HIV serology<br>• Hold acute serum and collect convalescent serum 10–14 d later for paired antibody testing<br>• Neuroimaging (MRI preferred to CT, if available)<br>• Chest imaging (Chest x-ray and/or CT)<br>• EEG}}
{{Family tree | | | | | | | | | | | | | | | | | | | | |!| | | | | }}
{{Family tree | | | | | | | | | | | | | | | | | | | | |!| | | | | }}
{{Family tree | | | | | | | | | | | | | | | | | | | | A01 | | | |A01= Evaluate further testing if additional risk factors are present}}
{{Family tree | | | | | | | | | | | | | | | | | | | | A01 | | | |A01= Evaluate further testing if additional risk factors are present}}
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{{Family tree | |`|-| E01 | | |)|-| E02 | | |)|-| E03 | | | | | |)|-| E04 | | |)|-| E05 | | |)|-| E06 |E01=Immunocompromised:<br>• CMV PCR<br>• HHV6/7 PCR<br>• HIV PCR (CSF)<br>• Toxoplasma gondii serology and/or PCR<br>• MTB testing<br>• Fungal testing<br>• WNV testing |E02=Africa:<br>• Malaria (blood smear)<br>• Trypanosomiasias (blood/CSF smear<br>• Serology from serum and CSF)<br>• Dengue testing |E03=Summer/Fall:<br>• Arbovirusd and tick-borne disease testing |E04=Psychotic features or movement disorder:<br>• Anti-NMDAR antibody (serum, CSF)<br>• Rabies testing<br>• Screen for malignancy<br>• Creutzfeld-Jakobs disease |E05=Elevated transaminases:<br>• Rickettsia serology<br>• Tick borne diseases testing |E06=Frontal lobe:<br>• Naegleria fowleri testing (CSF wet mount and PCRg) }}
{{Family tree | |`|-| E01 | | |)|-| E02 | | |)|-| E03 | | | | | |)|-| E04 | | |)|-| E05 | | |)|-| E06 |E01=Immunocompromised:<br>• CMV PCR<br>• HHV6/7 PCR<br>• HIV PCR (CSF)<br>• Toxoplasma gondii serology and/or PCR<br>• MTB testing<br>• Fungal testing<br>• WNV testing |E02=Africa:<br>• Malaria (blood smear)<br>• Trypanosomiasias (blood/CSF smear<br>• Serology from serum and CSF)<br>• Dengue testing |E03=Summer/Fall:<br>• Arbovirusd and tick-borne disease testing |E04=Psychotic features or movement disorder:<br>• Anti-NMDAR antibody (serum, CSF)<br>• Rabies testing<br>• Screen for malignancy<br>• Creutzfeld-Jakobs disease |E05=Elevated transaminases:<br>• Rickettsia serology<br>• Tick borne diseases testing |E06=Frontal lobe:<br>• Naegleria fowleri testing (CSF wet mount and PCRg) }}
{{Family tree | | | | | | | | |!| | | | | | |!| | | | | | | | | |!| | | | | | |!| | | | | | |!| | }}
{{Family tree | | | | | | | | |!| | | | | | |!| | | | | | | | | |!| | | | | | |!| | | | | | |!| | }}
{{Family tree | | | | | | | | |)|-| E02 | | |)|-| E03 | | | | | |)|-| E04 | | |)|-| E05 | | |)|-| E06 | |E02=Asia:<br>• Japanese encephalitis virus testing<br>• Dengue testing<br>• Malaria (blood smear)<br>• Nipah virus testing|E03=Cat exposure (particularly if with seizures, paucicellular CSF):<br>• Bartonella antibody (serum), ophthalmologic evaluation |E04=Prominent limbic symptoms:<br>• Autoimmune limbic encephalitis testing<br>• HHV6/7 PCR (CSF)<br>• Screen for malignancy |E05=CSF protein >100 mg/dL, or CSF glucose <2/3 peripheral glucose, or lymphocytic pleocytosis with subacute symptom onset:<br>• MTBtestingb<br>• Fungal testing |E06=Temporal lobe:<br>• VGKC antibodies (serum and CSF)<br>• HHV 6/7 PCR (CSF) }}
{{Family tree | | | | | | | | |)|-| E02 | | |)|-| E03 | | | | | |)|-| E04 | | |)|-| E05 | | |)|-| E06 | |E02=Asia:<br>• Japanese encephalitis virus testing<br>• Dengue testing<br>• Malaria (blood smear)<br>• Nipah virus testing|E03=Cat exposure (particularly if with seizures, paucicellular CSF):<br>• Bartonella antibody (serum), ophthalmologic evaluation |E04=Prominent limbic symptoms:<br>• Autoimmune limbic encephalitis testing<br>• HHV6/7 PCR (CSF)<br>• Screen for malignancy |E05=CSF protein >100 mg/dL, or CSF glucose <2/3 peripheral glucose, or lymphocytic pleocytosis with subacute symptom onset:<br>• MTB testingb<br>• Fungal testing |E06=Temporal lobe:<br>• VGKC antibodies (serum and CSF)<br>• HHV 6/7 PCR (CSF) }}
{{Family tree | | | | | | | | |!| | | | | | |!| | | | | | | | | |!| | | | | | |!| | | | | | |!| | }}
{{Family tree | | | | | | | | |!| | | | | | |!| | | | | | | | | |!| | | | | | |!| | | | | | |!| | }}
{{Family tree | | | | | | | | |)|-| E01 | | |)|-| E02 | | | | | |)|-| E03 | | |)|-| E04 | | |)|-| E05 | | |E01=Australia:<br>• Murray Valley encephalitis virus testingd<br>• Kunjin virus testingd<br>• Australian Bat Lyssavirus (ABLV) testing |E02=Tick exposure:<br>• Tick borne disease testing |E03=Rapid decompensation (particularly with animal bite history or prior travel to rabies-endemic areas):<br>• Rabies testing |E04=CSF protein >100 mg/dL or CSF glucose <2/3 peripheral glucose and neutrophilic predominance with acute symptom onset and recent antibiotic use:<br>• CSF PCR for S. pneumoniae and N. meningiditis |E05=Basal ganglia and/or thalamus:<br>• Arbovirusd testing<br>• MTB testing }}
{{Family tree | | | | | | | | |)|-| E01 | | |)|-| E02 | | | | | |)|-| E03 | | |)|-| E04 | | |)|-| E05 | | |E01=Australia:<br>• Murray Valley encephalitis virus testingd<br>• Kunjin virus testingd<br>• Australian Bat Lyssavirus (ABLV) testing |E02=Tick exposure:<br>• Tick borne disease testing |E03=Rapid decompensation (particularly with animal bite history or prior travel to rabies-endemic areas):<br>• Rabies testing |E04=CSF protein >100 mg/dL or CSF glucose <2/3 peripheral glucose and neutrophilic predominance with acute symptom onset and recent antibiotic use:<br>• CSF PCR for S. pneumoniae and N. meningiditis |E05=Basal ganglia and/or thalamus:<br>• Arbovirusd testing<br>• MTB testing }}
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{{Family tree | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |`|-| E06 |E06=Infarction or hemorrhage:<br>• MTB testing<br>• Fungal testing<br>• Respiratory virus testing }}
{{Family tree | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |`|-| E06 |E06=Infarction or hemorrhage:<br>• MTB testing<br>• Fungal testing<br>• Respiratory virus testing }}
{{Family tree/end}}
{{Family tree/end}}
{| class="wikitable"
{| class="wikitable"
|
|
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| colspan="1" rowspan="1" |'''Minor Criteria (2 required for possible encephalitis; ≥3 required for probable or confirmeda encephalitis):'''
| colspan="1" rowspan="1" |'''Minor Criteria (2 required for possible encephalitis; ≥3 required for probable or confirmeda encephalitis):'''
|-
|-
| colspan="1" rowspan="1" |Documented fever ≥38° C (100.4°F) within the 72 h before or after presentationb
| colspan="1" rowspan="1" |Documented fever ≥38° C (100.4°F) within the 72 h before or after presentation.
|-
|-
| colspan="1" rowspan="1" |Generalized or partial seizures not fully attributable to a preexisting seizure disorderc
| colspan="1" rowspan="1" |Generalized or partial seizures not fully attributable to a preexisting seizure disorder.
|-
|-
| colspan="1" rowspan="1" |New onset of focal neurologic findings
| colspan="1" rowspan="1" |New onset of focal neurologic findings.
|-
|-
| colspan="1" rowspan="1" |CSF WBC count ≥5/cubic mmd
| colspan="1" rowspan="1" |CSF WBC count ≥5/cubic mm.
|-
|-
| colspan="1" rowspan="1" |Abnormality of brain parenchyma on neuroimaging suggestive of encephalitis that is either new from prior studies or appears acute in onset
| colspan="1" rowspan="1" |Abnormality of brain parenchyma on neuroimaging suggestive of encephalitis that is either new from prior studies or appears acute in onset.
|-
|-
| colspan="1" rowspan="1" |Abnormality on electroencephalography that is consistent with encephalitis and not attributable to another cause.f
| colspan="1" rowspan="1" |Abnormality on electroencephalography that is consistent with encephalitis and not attributable to another cause.
|-
|-
|Do not modify
|Do not modify
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==Treatment==
==Treatment==
Shown below is an algorithm summarizing treatment of encephalitis according to the American Academy of Neurology guidelines:
Shown below is an algorithm summarizing treatment of herpetic encephalitis according to the Glasgow Institute of Neurological Sciences guidelines:<ref name="Kennedy20042">{{cite journal|last1=Kennedy|first1=P G E|title=VIRAL ENCEPHALITIS: CAUSES, DIFFERENTIAL DIAGNOSIS, AND MANAGEMENT|journal=Journal of Neurology, Neurosurgery & Psychiatry|volume=75|issue=90001|year=2004|pages=10i–15|issn=0022-3050|doi=10.1136/jnnp.2003.034280}}</ref><br><br>
{{Family tree/start}}
{{Family tree | | | | A01 |-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-|-| A02 | |A01= Suspected Herpes Simplex Encephalitis (HSE)| A02= Administer Acyclovir}}
{{Family tree | | | | |!| | | | | | | | | | | | | | | | | | | | | | | | | | |,|-|-|-|+|-|-|-|.| }}
{{Family tree | | | | A01 |-|-| A02 | | | | | | | | | | | | | | | | | | | | A03 | | A04 | | A05 | |A01=CT/MRI scan |A02=No mass but severe edema |A03=HSE proven<br>• 14-day course |A04=Possible HSE<br>• 10-day course |A05=Other diagnosis<br>• Stop acyclovir }}
{{Family tree | | | | |!| | | | |!| | | }}
{{Family tree | | | | A01 | | | |!| | |A01=No mass or severe edema }}
{{Family tree | | | | |!| | | | |!| | | }}
{{Family tree | | | | A01 |-|-| A02 |A01=Lumbar puncture |A02=Manitol and/or steroids }}
{{Family tree | | | | |!| | | | | | | }}
{{Family tree | | | | A01 | | | | | |A01=Supportive or alternative diagnosis }}
{{Family tree/end}}
<br><br>


==Do's==
==Dos==
 
*Rule out other causes of decreased level of [[consciousness]] and [[Personality changes|personality change]], such as [[drug abuse]].<ref name="Kennedy2004">{{cite journal|last1=Kennedy|first1=P G E|title=VIRAL ENCEPHALITIS: CAUSES, DIFFERENTIAL DIAGNOSIS, AND MANAGEMENT|journal=Journal of Neurology, Neurosurgery & Psychiatry|volume=75|issue=90001|year=2004|pages=10i–15|issn=0022-3050|doi=10.1136/jnnp.2003.034280}}</ref>
*Take a careful history examination of relatives when managing a comatose patient.<ref name="TunkelGlaser20082">{{cite journal|last1=Tunkel|first1=Allan R.|last2=Glaser|first2=Carol A.|last3=Bloch|first3=Karen C.|last4=Sejvar|first4=James J.|last5=Marra|first5=Christina M.|last6=Roos|first6=Karen L.|last7=Hartman|first7=Barry J.|last8=Kaplan|first8=Sheldon L.|last9=Scheld|first9=W. Michael|last10=Whitley|first10=Richard J.|title=The Management of Encephalitis: Clinical Practice Guidelines by the Infectious Diseases Society of America|journal=Clinical Infectious Diseases|volume=47|issue=3|year=2008|pages=303–327|issn=1537-6591|doi=10.1086/589747}}</ref>
*Perform routine full [[haematological]] and [[biochemical]] [[blood]] screen.<ref name="VenkatesanTunkel2013" />
*When performing a [[CSF]] [[analysis]], collect at least 20 ml, if possible; freeze at least 5-10 ml fluid; document opening pressure, [[WBC]] count with differential, [[RBC]] count, [[protein]], and [[glucose]]; [[Gram stain]] and [[Bacterial cultures|bacterial culture]].<ref name="VenkatesanTunkel2013" />
*Be aware that the absence of [[leukocytosis]], focal [[neurological]] [[signs]], [[fever]], [[headache]], and [[pleocytosis]], is more suggestive of [[encephalopathy]] rather than [[encephalitis]].<ref name="TunkelGlaser20082" />
*Perform a [[PCR]] for [[HSV|HSV-1/2]], [[VZV]], and [[enterovirus]] [[viruses]].<ref name="WeilGlaser2002">{{cite journal|last1=Weil|first1=Ana A.|last2=Glaser|first2=Carol A.|last3=Amad|first3=Zahwa|last4=Forghani|first4=Bagher|title=Patients with Suspected Herpes Simplex Encephalitis: Rethinking an Initial Negative Polymerase Chain Reaction Result|journal=Clinical Infectious Diseases|volume=34|issue=8|year=2002|pages=1154–1157|issn=1058-4838|doi=10.1086/339550}}</ref><ref name="KoskiniemiRantalaiho2001">{{cite journal|last1=Koskiniemi|first1=Marjaleena|last2=Rantalaiho|first2=Timo|last3=Piiparinen|first3=Heli|last4=von Bonsdorff|first4=Carl-Henrik|last5=Färkkilä|first5=Markus|last6=Järvinen|first6=Asko|last7=Kinnunen|first7=Esko|last8=Koskiniemi|first8=Suvi|last9=Mannonen|first9=Laura|last10=Muttilainen|first10=Marketta|last11=Linnavuori|first11=Kimmo|last12=Porras|first12=Jukka|last13=Puolakkainen|first13=Mirja|last14=Räihä|first14=Kirsti|last15=Salonen|first15=Eeva-Marjatta|last16=Ukkonen|first16=Pentti|last17=Vaheri|first17=Antti|last18=Valtonen|first18=Villei|title=Infections of the central nervous system of suspected viral origin: A collaborative study from Finland|journal=Journal of Neurovirology|volume=7|issue=5|year=2001|pages=400–408|issn=1355-0284|doi=10.1080/135502801753170255}}</ref>
*[[RPR]] is preferred over [[VDRL]] for [[Treponemal infection|treponemal]] detection.<ref name="VenkatesanTunkel2013" /><ref name="TunkelGlaser20082" />
*[[MRI]] is preferred over [[CT scan]] for [[neuroimaging]].<ref name="VenkatesanTunkel2013" />
*When significant [[edema]] is present in [[imaging]], give [[steroids]] and/or [[mannitol]] to reduce the [[intracranial pressure]] before [[lumbar puncture]].<ref name="TunkelGlaser20082" /><br />


==Don'ts==
==Don'ts==
*Do not delay [[antiviral]] [[treatment]], since [[mortality]] may reach up to 70% when not given.<ref name="Kennedy2004" /><ref name="WhitleyGnann2002">{{cite journal|last1=Whitley|first1=Richard J|last2=Gnann|first2=John W|title=Viral encephalitis: familiar infections and emerging pathogens|journal=The Lancet|volume=359|issue=9305|year=2002|pages=507–513|issn=01406736|doi=10.1016/S0140-6736(02)07681-X}}</ref>
*Do no perform [[lumbar puncture]] before [[neuroimaging]].<ref name="TunkelGlaser20082" />


==References==
==References==
{{Reflist|2}}
{{Reflist|2}}
[[Category:Up-To-Date]]

Latest revision as of 20:17, 19 February 2021

Encephalitis Resident Survival Guide Microchapters
Overview
Causes
Diagnosis
Treatment
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Moises Romo M.D.

Synonyms and Keywords: encephalitis management, encephalitis workup, encephalitis approach,encephalitis management, encephalitis treatment, encephalitis diagnosis

Overview

Encephalitis refers to the inflammation of the brain parenchyma acompanied of neurological dysfunction. The causes of encephalitis are mostly infectious, being viruses, bacteria, fungi, or parasites the possible agents. Presentation usually involves headache, fever, confusion, neck stiffness (Kernig and Brudzinski signs), and vomiting. Diagnosis is typically based on clinical presentation and supported by blood tests, medical imaging, and analysis of cerebrospinal fluid. Rapid identification of encephalitis is crucial to reduce sequelae. Management is directed against the affecting agent (antivirals, antibiotics), reducing swelling, and supportive measures.

Causes

Life Threatening Causes

Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.

Common Causes

Infectious

Diagnosis

Shown below is an algorithm summarizing the diagnosis of encephalitis according to the International Encephalitis Consortium guidelines:[1]

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Patient suspicious for encephalitis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
PERFORM:
• CSF analysis
• Routine blood testing
• Blood cultures
• HSV-1/2 PCR
• VZV PCR
• Enterovirus PCR
• Cryptococcal antigen and/or India Ink staining
• Oligoclonal bands and IgG index
• VDRL
• HIV serology
• Hold acute serum and collect convalescent serum 10–14 d later for paired antibody testing
• Neuroimaging (MRI preferred to CT, if available)
• Chest imaging (Chest x-ray and/or CT)
• EEG
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Evaluate further testing if additional risk factors are present
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Host factors
 
 
 
 
Geographic factors
 
 
 
 
Season and exposure
 
 
 
 
 
 
 
Specific signs and symptoms
 
 
 
 
Laboratory features
 
 
 
 
Neuroimaging features
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Immunocompromised:
• CMV PCR
• HHV6/7 PCR
• HIV PCR (CSF)
• Toxoplasma gondii serology and/or PCR
• MTB testing
• Fungal testing
• WNV testing
 
 
 
 
 
Africa:
• Malaria (blood smear)
• Trypanosomiasias (blood/CSF smear
• Serology from serum and CSF)
• Dengue testing
 
 
 
 
 
Summer/Fall:
• Arbovirusd and tick-borne disease testing
 
 
 
 
 
 
 
 
Psychotic features or movement disorder:
• Anti-NMDAR antibody (serum, CSF)
• Rabies testing
• Screen for malignancy
• Creutzfeld-Jakobs disease
 
 
 
 
 
Elevated transaminases:
• Rickettsia serology
• Tick borne diseases testing
 
 
 
 
 
Frontal lobe:
• Naegleria fowleri testing (CSF wet mount and PCRg)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Asia:
• Japanese encephalitis virus testing
• Dengue testing
• Malaria (blood smear)
• Nipah virus testing
 
 
 
 
 
Cat exposure (particularly if with seizures, paucicellular CSF):
• Bartonella antibody (serum), ophthalmologic evaluation
 
 
 
 
 
 
 
 
Prominent limbic symptoms:
• Autoimmune limbic encephalitis testing
• HHV6/7 PCR (CSF)
• Screen for malignancy
 
 
 
 
 
CSF protein >100 mg/dL, or CSF glucose <2/3 peripheral glucose, or lymphocytic pleocytosis with subacute symptom onset:
• MTB testingb
• Fungal testing
 
 
 
 
 
Temporal lobe:
• VGKC antibodies (serum and CSF)
• HHV 6/7 PCR (CSF)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Australia:
• Murray Valley encephalitis virus testingd
• Kunjin virus testingd
• Australian Bat Lyssavirus (ABLV) testing
 
 
 
 
 
Tick exposure:
• Tick borne disease testing
 
 
 
 
 
 
 
 
Rapid decompensation (particularly with animal bite history or prior travel to rabies-endemic areas):
• Rabies testing
 
 
 
 
 
CSF protein >100 mg/dL or CSF glucose <2/3 peripheral glucose and neutrophilic predominance with acute symptom onset and recent antibiotic use:
• CSF PCR for S. pneumoniae and N. meningiditis
 
 
 
 
 
Basal ganglia and/or thalamus:
• Arbovirusd testing
• MTB testing
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Europe:
• Tick-borne encephalitis virus (serology)
 
 
 
 
 
Animal bite/bat exposure:
• Rabies testing
 
 
 
 
 
 
 
 
Respiratory symptoms:
• Mycoplasma pneumoniae serology and throat PCR (if either positive, then do CSF PCR)
• Respiratory virus testing
 
 
 
 
 
CSF eosinophilia:
• MTB testingb
• Fungal testingc
• Baylisascaris procyonis antibody (serum)
• Angiostrongylus cantonensis and Gnathostomasp. testing
 
 
 
 
 
Brainstem:
• Arbovirus testingd
• Listeria PCR(if available)
• Brucella antibody (serum)
• MTB testing
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Southern Europe:
• WNV testing
• Toscana virus testing
 
 
 
 
 
Swimming or diving in warm freshwater or nasal/sinus irrigation:
• Naegleria fowleri (CSF wet mount and PCR)
 
 
 
 
 
 
 
 
Acute flaccid paralysis:
• Arbovirus testingd
• Rabies testing
 
 
 
 
 
RBCs in CSF:
• Naegleria fowleri testing
 
 
 
 
 
Cerebellum:
• EBV PCR (CSF) and serology
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Central and South America:
• Dengue testingd
• Malaria (blood smear)
• WNV
• Venezuelan equine encephalitis testing
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Parkinsonism:
• Arbovirus testingd
• Toxoplasma serology
 
 
 
 
 
Hyponatremia—anti:
• VGKC antibody (serum)
• MTB testing
 
 
 
 
 
Diffuse cerebral edema:
• Respiratory virus testing
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
North America:
• Geographically appropriate arboviral testing (eg, WNV, Powassan, LaCrosse, Eastern Equine Encephalitis virusesd, Lyme(serum ELISA and Western blot)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Nonhealing skin lesions:
• Balamuthia mandrillaris
• Acanthamoeba testing
 
 
 
 
 
 
 
 
 
 
 
 
Space occupying and/or ring-enhancing lesions:
• MTB testingb
• Fungal testingc
• Balamuthia mandrillaris and Acanthamoeba testingg
• Toxoplasma serology
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hydrocephalus and/or basilar meningeal enhancement:
• MTB testingb
• Fungal testing
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Infarction or hemorrhage:
• MTB testing
• Fungal testing
• Respiratory virus testing
 
 

Diagnostic Criteria for Encephalitis and Encephalopathy of Presumed Infectious or Autoimmune Etiology according to the International Encephalitis Consortium

Major Criterion (required):
Patients presenting to medical attention with altered mental status (defined as decreased or altered level of consciousness, lethargy, or personality change) lasting ≥24 h with no alternative cause identified.
Minor Criteria (2 required for possible encephalitis; ≥3 required for probable or confirmeda encephalitis):
Documented fever ≥38° C (100.4°F) within the 72 h before or after presentation.
Generalized or partial seizures not fully attributable to a preexisting seizure disorder.
New onset of focal neurologic findings.
CSF WBC count ≥5/cubic mm.
Abnormality of brain parenchyma on neuroimaging suggestive of encephalitis that is either new from prior studies or appears acute in onset.
Abnormality on electroencephalography that is consistent with encephalitis and not attributable to another cause.
Do not modify

Treatment

Shown below is an algorithm summarizing treatment of herpetic encephalitis according to the Glasgow Institute of Neurological Sciences guidelines:[2]

 
 
 
Suspected Herpes Simplex Encephalitis (HSE)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Administer Acyclovir
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CT/MRI scan
 
 
No mass but severe edema
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
HSE proven
• 14-day course
 
Possible HSE
• 10-day course
 
Other diagnosis
• Stop acyclovir
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No mass or severe edema
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lumbar puncture
 
 
Manitol and/or steroids
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Supportive or alternative diagnosis
 
 
 
 
 



Dos

Don'ts

References

  1. 1.0 1.1 1.2 1.3 1.4 Venkatesan, A.; Tunkel, A. R.; Bloch, K. C.; Lauring, A. S.; Sejvar, J.; Bitnun, A.; Stahl, J-P.; Mailles, A.; Drebot, M.; Rupprecht, C. E.; Yoder, J.; Cope, J. R.; Wilson, M. R.; Whitley, R. J.; Sullivan, J.; Granerod, J.; Jones, C.; Eastwood, K.; Ward, K. N.; Durrheim, D. N.; Solbrig, M. V.; Guo-Dong, L.; Glaser, C. A.; Sheriff, Heather; Brown, David; Farnon, Eileen; Messenger, Sharon; Paterson, Beverley; Soldatos, Ariane; Roy, Sharon; Visvesvara, Govinda; Beach, Michael; Nasci, Roger; Pertowski, Carol; Schmid, Scott; Rascoe, Lisa; Montgomery, Joel; Tong, Suxiang; Breiman, Robert; Franka, Richard; Keuhnert, Matt; Angulo, Fred; Cherry, James (2013). "Case Definitions, Diagnostic Algorithms, and Priorities in Encephalitis: Consensus Statement of the International Encephalitis Consortium". Clinical Infectious Diseases. 57 (8): 1114–1128. doi:10.1093/cid/cit458. ISSN 1537-6591.
  2. Kennedy, P G E (2004). "VIRAL ENCEPHALITIS: CAUSES, DIFFERENTIAL DIAGNOSIS, AND MANAGEMENT". Journal of Neurology, Neurosurgery & Psychiatry. 75 (90001): 10i–15. doi:10.1136/jnnp.2003.034280. ISSN 0022-3050.
  3. 3.0 3.1 Kennedy, P G E (2004). "VIRAL ENCEPHALITIS: CAUSES, DIFFERENTIAL DIAGNOSIS, AND MANAGEMENT". Journal of Neurology, Neurosurgery & Psychiatry. 75 (90001): 10i–15. doi:10.1136/jnnp.2003.034280. ISSN 0022-3050.
  4. 4.0 4.1 4.2 4.3 4.4 Tunkel, Allan R.; Glaser, Carol A.; Bloch, Karen C.; Sejvar, James J.; Marra, Christina M.; Roos, Karen L.; Hartman, Barry J.; Kaplan, Sheldon L.; Scheld, W. Michael; Whitley, Richard J. (2008). "The Management of Encephalitis: Clinical Practice Guidelines by the Infectious Diseases Society of America". Clinical Infectious Diseases. 47 (3): 303–327. doi:10.1086/589747. ISSN 1537-6591.
  5. Weil, Ana A.; Glaser, Carol A.; Amad, Zahwa; Forghani, Bagher (2002). "Patients with Suspected Herpes Simplex Encephalitis: Rethinking an Initial Negative Polymerase Chain Reaction Result". Clinical Infectious Diseases. 34 (8): 1154–1157. doi:10.1086/339550. ISSN 1058-4838.
  6. Koskiniemi, Marjaleena; Rantalaiho, Timo; Piiparinen, Heli; von Bonsdorff, Carl-Henrik; Färkkilä, Markus; Järvinen, Asko; Kinnunen, Esko; Koskiniemi, Suvi; Mannonen, Laura; Muttilainen, Marketta; Linnavuori, Kimmo; Porras, Jukka; Puolakkainen, Mirja; Räihä, Kirsti; Salonen, Eeva-Marjatta; Ukkonen, Pentti; Vaheri, Antti; Valtonen, Villei (2001). "Infections of the central nervous system of suspected viral origin: A collaborative study from Finland". Journal of Neurovirology. 7 (5): 400–408. doi:10.1080/135502801753170255. ISSN 1355-0284.
  7. Whitley, Richard J; Gnann, John W (2002). "Viral encephalitis: familiar infections and emerging pathogens". The Lancet. 359 (9305): 507–513. doi:10.1016/S0140-6736(02)07681-X. ISSN 0140-6736.