Encephalitis resident survival guide

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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:
• MTBtestingb
• 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
 
 
 
 
 



Do's

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.