Encephalitis: Difference between revisions

Latest revision as of 16:46, 25 January 2022

Infection of the brain parenchyma causing clouding of the sensorium
Some overlap with meningitis

Differential Diagnosis

Common causes include HSV, VZV, and enterovirus in developed countries
Consider rabies virus, Japanese encephalitis virus, West Nile virus, tickborne encephalitis virus, and St. Louis encephalitis virus depending on travel history
Infectious
- Viruses
- Bacteria
  - Mycoplasma pneumoniae
  - Listeria monocytogenes
  - Borrelia burgdorferi (Lyme disease)
  - Coxiella burnetii
  - Bartonella henselae or B. quintana
- Other
Non-infectious (including post-infectious)
Cryptogenic in 50-70%

Investigations

Lumbar puncture for viral culture or PCR
MRI is the best neuroimaging; CT if MRI not available
EEG is rarely helpful except to rule out non-convulsive status epilepticus

MRI

Finding	Differential Diagnosis
arteritis and infarctions	Varicella-zoster virus, Nipah virus, Rickettsia rickettsii, Treponema pallidum pallidum
calcifications	CMV (cortical), Toxoplasma (periventricular), Taenia solium
cerebellar lesions	VZV, EBV, Mycoplasma pneumoniae
basal ganglia, thalamus, or brainstem lesions	EBV, eastern equine encephalitis virus, Murray Valley encephalitis virus, St. Louis encephalitis virus, Japanese encephalitis virus, West Nile virus, enterovirus A71, influenza virus, prion disease, Tropheryma whipplei, Listeria monocytogenes
hydrocephalus	Mycobacterium tuberculosis, Cryptococcus neoformans, Coccidioides immitis, Histoplasma capsulatum, Balamuthia mandrillaris
space-occupying lesions	Toxoplasma gondii, Balamuthia mandrillaris, Acanthamoeba, Taenia solium
subependymal enhancement	CMV
temporal or frontal lobe involvement	HSV, VZV, HHV-6, West Nile virus, enterovirus, Treponema pallidum pallidum (medial lobes)
white matter abnormalities	VZV, CMV, EBV, HHV-6, HIV, Nipah virus, JC virus, measles virus, Baylisascaris procyonis, acute disseminated encephalomyelitis

Management

Empiric acyclovir 10 mg/kg IV q8h for suspected HSV or VZV encephalitis
Add doxycycline if rickettsiosis or ehrlichiosis is possible

@@ Line 1: / Line 1: @@
-* Infection of the brain parenchyma causing clouding of the sensorium
+*Infection of the brain parenchyma causing clouding of the sensorium
-* Some overlap with [[Meningitis|meningitis]]
+*Some overlap with [[meningitis]]
-= Differential Diagnosis =
+==Differential Diagnosis==
+*Common causes include [[HSV]], [[VZV]], and [[enterovirus]] in developed countries
-* Infectious
+*Consider [[rabies virus]], [[Japanese encephalitis virus]], [[West Nile virus]], [[tickborne encephalitis virus]], and [[St. Louis encephalitis virus]] depending on travel history
-** Viruses
+*Infectious
-*** Enteroviruses
+**Viruses
-*** Eastern or Western equine encephalitis, Japanese encephalitis, Murray Valley encephalitis, St. Louis encephalitis, West Nile virus
+***[[Herpes simplex encephalitis|Herpes simplex virus]]
-*** Rabies
-*** Hendra virus
+***[[Varicella-zoster virus]]
+***[[Enterovirus|Enteroviruses]]
-*** Nipah virus
+***[[Eastern equine encephalitis virus|Eastern]] or [[Western equine encephalitis virus]], [[Japanese encephalitis virus]], [[Murray Valley encephalitis virus]], [[St. Louis encephalitis virus]], [[West Nile virus]]
-*** Tickborne encephalitis, La Crosse virus, Powassan virus
+***[[Rabies virus]]
-** Bacteria
+***[[Hendra virus]]
-*** ''Mycoplasma pneumoniae''
+***[[Nipah virus]]
-*** ''Listeria monocytogenes''
+***[[Tickborne encephalitis virus]], [[La Crosse virus]], [[Powassan virus]]
-*** ''Borrelia burgdorferi'' (Lyme disease)
+**Bacteria
-*** ''Coxiella burnetii''
+***''[[Mycoplasma pneumoniae]]''
-*** ''Bartonella henselae'' or ''B. quintana''
+***''[[Listeria monocytogenes]]''
-** Other
+***''[[Borrelia burgdorferi]]'' (Lyme disease)
-*** ''Cryptococcus neoformans''
-*** ''Toxoplasma gondii''
+***''[[Coxiella burnetii]]''
+***''[[Bartonella henselae]]'' or ''[[B. quintana]]''
-*** ''Bayliscarias procyonis''
+**Other
-*** Prion disease (CJD)
+***''[[Cryptococcus neoformans]]''
-* Non-infectious (including post-infectious)
+***''[[Toxoplasma gondii]]''
-** Acute disseminated encephalomyelitis (ADEM)
+***''[[Bayliscarias procyonis]]''
-** Vasculitis
+***[[Prion disease]] ([[CJD]])
-** Collagen vascular disorders
+*Non-infectious (including post-infectious)
-** Paraneoplastic syndromes
+**[[Acute disseminated encephalomyelitis]] (ADEM)
+**[[Vasculitis]]
+**[[Collagen vascular disorders]]
+**[[Paraneoplastic syndromes]]
+*'''Cryptogenic in 50-70%'''
-= Investigations =
+==Investigations==
-* Lumbar puncture for viral culture or PCR
+*Lumbar puncture for viral culture or PCR
-* MRI is the best neuroimaging; CT if MRI not available
+*MRI is the best neuroimaging; CT if MRI not available
-* EEG is rarely helpful except to rule out non-convulsive status epilepticus
+*EEG is rarely helpful except to rule out non-convulsive status epilepticus
+===MRI===
-= Management =
+{| class="wikitable"
+!Finding
+!Differential Diagnosis
+|-
+|arteritis and infarctions
+|[[Varicella-zoster virus]], [[Nipah virus]], [[Rickettsia rickettsii]], [[Treponema pallidum pallidum]]
+|-
+|calcifications
+|[[CMV]] (cortical), [[Toxoplasma]] (periventricular), [[Taenia solium]]
+|-
+|cerebellar lesions
+|[[VZV]], [[EBV]], [[Mycoplasma pneumoniae]]
+|-
+|basal ganglia, thalamus, or brainstem lesions
+|[[EBV]], [[eastern equine encephalitis virus]], [[Murray Valley encephalitis virus]], [[St. Louis encephalitis virus]], [[Japanese encephalitis virus]], [[West Nile virus]], [[enterovirus]] A71, [[influenza virus]], [[prion disease]], [[Tropheryma whipplei]], [[Listeria monocytogenes]]
+|-
+|hydrocephalus
+|[[Mycobacterium tuberculosis]], [[Cryptococcus neoformans]], [[Coccidioides immitis]], [[Histoplasma capsulatum]], [[Balamuthia mandrillaris]]
+|-
+|space-occupying lesions
+|[[Toxoplasma gondii]], [[Balamuthia mandrillaris]], [[Acanthamoeba]], [[Taenia solium]]
+|-
+|subependymal enhancement
+|[[CMV]]
+|-
+|temporal or frontal lobe involvement
+|[[HSV]], [[VZV]], [[HHV-6]], [[West Nile virus]], [[enterovirus]], [[Treponema pallidum pallidum]] (medial lobes)
+|-
+|white matter abnormalities
+|[[VZV]], [[CMV]], [[EBV]], [[HHV-6]], [[HIV]], [[Nipah virus]], [[JC virus]], [[measles virus]], [[Baylisascaris procyonis]], [[acute disseminated encephalomyelitis]]
+|}
+==Management==
-* Acyclovir for syspected HSV or VZV encephalitis
+*Empiric [[acyclovir]] 10 mg/kg IV q8h for suspected HSV or VZV encephalitis
+*Add [[doxycycline]] if [[Rickettsiae|rickettsiosis]] or [[ehrlichiosis]] is possible
 [[Category:CNS infections]]