Encephalitis lethargica (EL) or von Economo disease is an atypical form of encephalitis. Also known as "sleepy sickness" or 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 1917, EL attacks the brain, leaving some victims in a statue-like condition, speechless and motionless. Between 1915 and 1926, an epidemic of encephalitis lethargica spread around the world; no recurrence of the epidemic has since been reported, though isolated cases continue to occur.

Symptoms

Encephalitis lethargica is characterized by high fever, sore throat, headache, double vision, delayed physical and mental response, sleep inversion, catatonia and lethargy. 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, research in 2004 suggested that the disease is due to an immune reaction. In this study, many of the people with encephalitis lethargica had experienced recent pharyngitis and the authors found some evidence linking the reaction to prior strep throat. They hypothesised that encephalitis lethargica, Sydenham's chorea and PANDAS (paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) are mediated by variations of the post-streptococcal immune response. 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.

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. 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 L-DOPA could relieve some 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 on 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, in the last few episodes of the second series.

It is also believed that during 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.

References

External links

• National Institute of Neurological Disorders and Stroke
• Mystery of the Forgotten Plague: BBC news item about the tracing of the infectious agent in encephalitis lethargica
• : BBC Horizon programme suggesting linkage between encephalitis lethargica and Spanish flu pandemic
• BBC health article on encephalitis lethargica