Encephalitis lethargica. What is still wrong?

Encephalitis lethargica developed in epidemic from 1919 to 1926 in Europe and throughout the world. From the clinical point of view, the disturbances of consciousness and alertness and the possible outcomes of a postencephalitic Parkinsonism has attracted much attention. For a long time, it was thought that such a disease may still occur sporadically. In this review, the authors examined historical and current pictures of epidemics that may be related to Encephalitis lethargica. The previous Nona and Russian Influenza exhibited frequent neurological symptoms. The Spanish flu, formerly related to Encephalitis lethargica, would appear an epidemic that had its development in a partially overlapping period. The current pandemic linked to COVID-19 sometimes has aspects that can resemble Encephalitis lethargica. Based on historical analysis and the more recent immunological data, it could be suggested that Encephalitis lethargica was an autoimmune encephalitis that arose in a secondary form to the action of a viral agent. It cannot be ruled out that this agent was a coronavirus. From the nosological point of view, the term Encephalitis lethargica should be abolished in designating autoimmune encephalitis pictures that run sporadically.

The first psychiatric pandemic: Encephalitis lethargica, 1917-27.

Finding a link between COVID-19 and subsequent psychiatric symptoms has resulted in renewed interest in the psychiatric sequelae of pandemics. The first such instance was apparently the encephalitis lethargica pandemic which arose around the time of the First World War, moving in the shadow of a repiratory virus pandemic. The epidemic of encephalitis lethargica (EL), or Von Economo's Disease, in the years 1917-27 was the first pandemic involving the central nervous system. It moved in some places in parallel with the Great Flu Pandemic but does not seem to have been caused by it. Unlike the coronavirus, pandemic EL affected children heavily, leading often to bizarre changes in character and personality. It often left sequelae lasting for decades in the form of postencephalitic Parkinsonism (PEP). Unlike the coronavirus, it had a high mortality of around 20 percent. Although encephalitis lethargica involved a number of systems, psychiatric morbidity was most prominent and entailed severe depression, mania, catatonia and psychosis. It ended without therapeutic or public-health measures; today, sporadic cases of EL continue to be reported. The hypothesis is that we can derive from the EL psychiatric pandemic certain lessons that might be useful in studying tardive COVID symptoms today.