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

## Common Causes
Infectious
- Herpes simplex
- Mumps
- Rubella
- Epstein-Barr virus
- Varicella zoster

# Diagnosis
Shown below is an algorithm summarizing the diagnosis of encephalitis according to the International Encephalitis Consortium guidelines:

# Treatment
Shown below is an algorithm summarizing treatment of herpetic encephalitis according to the Glasgow Institute of Neurological Sciences guidelines:

# Dos
- Rule out other causes of decreased level of consciousness and personality change, such as drug abuse.
- Take a careful history examination of relatives when managing a comatose patient.
- Perform routine full haematological and biochemical blood screen.
- 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 culture.
- Be aware that the absence of leukocytosis, focal neurological signs, fever, headache, and pleocytosis, is more suggestive of encephalopathy rather than encephalitis.
- Perform a PCR for HSV-1/2, VZV, and enterovirus viruses.
- RPR is preferred over VDRL for treponemal detection.
- MRI is preferred over CT scan for neuroimaging.
- When significant edema is present in imaging, give steroids and/or mannitol to reduce the intracranial pressure before lumbar puncture.

# Don'ts
- Do not delay antiviral treatment, since mortality may reach up to 70% when not given.
- Do no perform lumbar puncture before neuroimaging.