Encephalitis lethargica
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Overview
Encephalitis lethargica (EL) 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 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] During the outbreak over 5 million died from disease-related causes.
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.
A BBC Horizon television programme on the potential for a world-wide outbreak of H5N1 Bird Flu broadcast on November 7, 2006 postulated that the 1920s outbreak of encephalitis lethargica might have been as a direct, delayed pathological result of the Spanish Flu pandemic.
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.[3] 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.
References
- ↑ 1.0 1.1 1.2 Dale RC, Church AJ, Surtees RA; et al. (2004). "Encephalitis lethargica syndrome: 20 new cases and evidence of basal ganglia autoimmunity". Brain. 127 (Pt 1): 21–33. doi:10.1093/brain/awh008. PMID 14570817.
- ↑ Reid AH, McCall S, Henry JM, Taubenberger JK (2001). "Experimenting on the past: the enigma of von Economo's encephalitis lethargica". J. Neuropathol. Exp. Neurol. 60 (7): 663–70. PMID 11444794.
- ↑ Blunt SB, Lane RJ, Turjanski N, Perkin GD (1997). "Clinical features and management of two cases of encephalitis lethargica". Mov. Disord. 12 (3): 354–9. doi:10.1002/mds.870120314. PMID 9159730.
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
- [2]: BBC Horizon programme suggesting linkage between encephalitis lethargica and Spanish flu pandemic
- BBC health article on encephalitis lethargica
- NIH.gov
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