Encephalitis lethargica

Encephalitis lethargica (EL) or von Economo disease is an atypical form of encephalitis. Also known as sleeping sickness (though different from the sleeping sickness transmitted by the tsetse fly), EL is a devastating illness that swept the world in the 1920s and then vanished as quickly as it had appeared. First described by the neurologist Constantin von Economo (1876-1931) in 1916, EL attacks the brain, leaving some victims in a statue-like condition, speechless and motionless.^[1] Between 1917 and 1928, an epidemic of encephalitis lethargica spread throughout the world, but no recurrence of the epidemic has since been reported, though isolated cases continue to occur.^[2][3] During the outbreak over 5 million died from disease-related causes.

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Symptoms

Encephalitis lethargica is characterized by high fever, sore throat, headache, double vision, delayed physical and mental response, sleep inversion, catatonia and lethargy.^[1] In acute cases, patients may enter a coma-like state (akinetic mutism). Patients may also experience abnormal eye movements, parkinsonism, upper body weakness, muscular pains, tremors, neck rigidity, and behavioral changes including psychosis.

Postencephalitic Parkinson's disease may develop after a bout of encephalitis, sometimes as long as a year after the start of the illness.

Cause

The cause of encephalitis lethargica is not known for certain. However, recent research suggests that the disease is due to a massive immune reaction to an infection by the streptococcus-like bacterium, diplococcus.^[1] There is also some evidence of an autoimmune origin with antibodies (IgG) from patients with EL binding to neurons in the basal ganglia and mid-brain. It had been hypothesised that encephalitis lethargica, Sydenham's chorea and PANDAS (paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) are mediated by the same post-streptococcal immune response.

Treatment

Treatment for encephalitis lethargica in the early stages is patient stabilization, which may be very difficult. There is little evidence so far of a consistent effective treatment for the initial stages, though some patients given steroids have seen improvement.^[4] Other patients have been less fortunate, and the disease then becomes progressive, with evidence of brain damage similar to Parkinson's disease. Treatment is then symptomatic. Levodopa (L-dopa) and other anti-parkinson drugs often produce dramatic responses. However in most of the patients who were given L-Dopa in the 1960s, the amelioration of the disease was short lived.

The course of encephalitis lethargica varies depending upon complications or accompanying disorders.

Popular culture

The discovery that levodopa could produce some amelioration of the symptoms was described in the book Awakenings by Oliver Sacks in 1973. The book was used by Harold Pinter as the basis of his one-act play A Kind of Alaska, performed in 1982 starring Judi Dench. Awakenings is also the title of a 1990 movie starring Robin Williams based upon the book.

The disease is also mentioned in Neil Gaiman's The Sandman. In this fictional comic book series, the disease is in some way caused by the capture and imprisonment of Morpheus, the King of Dreams. In his absence, people on Earth mysteriously fall prey to the sleeping sickness as he cannot be there to maintain and restore order.

The disease is researched and mentioned in the Canadian television show ReGenesis.

It is also believed that in The Salem Witch trials the girls that were apparently bewitched could have possibly been affected by the disease. The visions of spirits could have been the double vision that is possible and the fits and tremors the girls experienced are all possible symptoms.

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