Encephalitis lethargica

Dr Schertz et al.

Encephalitis lethargica (EL) is a rare disease that is also known as von Economo encephalitis. It affects the midbrain and basal ganglia, and the exact aetiology is unknown. 

Symptoms are initially that of pharyngitis followed by lethargy, extrapyramidal movements (parkinsonism and dyskinesias), neuropsychiatric
disturbance (obsessive, compulsive disorder, catatonia, mutism, apathy and conduct disorders), and ocular movement disorder (oculogyric crises).

The exact aetiology is unknown but there is lymphocyte infiltration of the midbrain and basal ganglia.

Markers

Autoantibodies reactive against human basal ganglia antigens present in the majority of EL patients. 

MRI

Brain MRI demonstrates inflammatory changes localised to the deep grey matter
in 40% of patients.

  • T1: low signal
  • T2/FLAIR: high signal in the basal ganglia (including the substantia nigra), midbrain, thalamus, cerebral peduncle and/or temporal cortex
  • T1 C+ (Gd): leptomeningeal and focal patchy enhancement 
  • DWI/ADC: isointense without restriction of ADC
Nuclear medicine
  • PET-CT: increased glucose metabolism in the basal ganglia

Treatment approaches to encephalitis lethargica include immunomodulating therapies and steroids.

First described by von Economo in 1916 during an epidemic affecting 500,000 people worldwide in 1916-1927. There have been no further epidemics of EL since the 1920s, although sporadic cases have continued to be reported.

General imaging differential considerations include:

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Article information

rID: 42574
Section: Pathology
Synonyms or Alternate Spellings:
  • von Economo encephalitis

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