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Encephalitis Lethargica

Last updated April 18, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Encephalitis Lethargica (EL) is a disease characterized by high fever, headache, double vision, delayed physical and mental response, extreme tiredness (lethargy), and sometimes coma.


What are the other Names for this Condition? (Also known as/Synonyms)

  • EL (Encephalitis Lethargica)
  • Von Economo’s Disease

What is Encephalitis Lethargica? (Definition/Background Information)

  • Encephalitis Lethargica (EL) is a disease characterized by high fever, headache, double vision, delayed physical and mental response, extreme tiredness (lethargy), and sometimes coma
  • Patients may also experience abnormal eye movements, upper body weakness, muscle pain, tremors, neck rigidity, and behavioral changes including psychosis
  • A worldwide epidemic of EL occurred from 1917 to 1928 with more than one million reported cases. Although occasional cases are reported with similar symptoms, EL epidemics have not recurred
  • The cause of this condition is unknown, but a viral origin is suspected
  • Treatment depends on a person's symptoms. Levodopa and other antiparkinson drugs may be effective in alleviating some symptoms

(Source: Encephalitis Lethargica; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Encephalitis Lethargica? (Age and Sex Distribution)

  • Encephalitis Lethargica is a rare condition that may be seen in both children and adults
  • Both males and females may be affected
  • Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Encephalitis Lethargica? (Predisposing Factors)

  • Currently, no risk factors have been clearly identified for Encephalitis Lethargica

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Encephalitis Lethargica? (Etiology)

  • The cause of Encephalitis Lethargica is unknown, but a viral origin is suspected

(Source: Encephalitis Lethargica; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

What are the Signs and Symptoms of Encephalitis Lethargica?

The signs and symptoms of Encephalitis Lethargica may include:

  • High fever, headache
  • Double vision
  • Delayed physical and mental response
  • Extreme tiredness (lethargy)
  • Coma (sometimes)

Patients may also experience the following:

  • Abnormal eye movements
  • Upper body weakness
  • Muscle pain, tremors
  • Neck rigidity
  • Behavioral changes including psychosis

(Source: Encephalitis Lethargica; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Encephalitis Lethargica Diagnosed?

Encephalitis Lethargica is diagnosed on the basis of the following information:

  • Complete physical examination
  • Thorough medical history evaluation
  • Assessment of signs and symptoms
  • Laboratory tests
  • Imaging studies
  • Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Encephalitis Lethargica?

The complications of Encephalitis Lethargica may include:

  • Severe fatigue
  • Coma

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Encephalitis Lethargica Treated?

  • Treatment of Encephalitis Lethargica depends on a person's symptoms
  • Levodopa and other antiparkinson drugs may be effective in alleviating some symptoms

(Source: Encephalitis Lethargica; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How can Encephalitis Lethargica be Prevented?

Currently, Encephalitis Lethargica may not be preventable, since the exact cause of this condition is unknown.

What is the Prognosis of Encephalitis Lethargica? (Outcomes/Resolutions) 

  • The prognosis of Encephalitis Lethargica is dependent upon the severity of the signs and symptoms and associated complications, if any
  • Individuals with mild conditions have better prognosis than those with severe symptoms and complications
  • Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Encephalitis Lethargica:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: April 18, 2018
Last updated: April 18, 2018