ABSTRACT
Von Economo’s encephalitis, known by several other appellations, including “encephalitis lethargica” and “sleeping sickness” among others was a fear-inspiring epidemic disease largely confined to the beginning of the twentieth century. The disease was of presumed viral etiology. The technical abilities of the scientists attempting to unravel the origins of the disorder precluded definite attribution. Some have attributed it to the then prevalent and deadly influenza epidemic, but contemporary physicians as well as other strong lines of evidence suggest that it did not occur as a consequence of the influenza virus. The neurological disorder characterized by an encephalopathy often with meningitic features was generally preceded by a nondescript upper respiratory infection. It generally followed three patterns of expression in the acute phase, a somnolent-ophthalmoplegic form, a hyperkinetic form, or an amyostatic-akinetic form. Chronically, it often evolved into a Parkinsonian disorder and in the middle of the twentieth century accounted for large numbers of Parkinson patients. Indeed, the initial trials of l-dopa in Parkinsonism were performed in many patients with this disorder. Pathological studies revealed that perivascular inflammation with associated neuronophagia and microglial nodules were mainly centered in the upper brainstem and diencephalon. Rare cases concordant with this disorder continue to be reported, but fortunately, these have been exceptionally rare.
