Modern conception of encephalitis lethargica

Abstract

1. Encephalitis lethargica is an epidemic disease of the central nervous system quite distinct from similar affections such as acute poliomyelitis and cerebro-spinal fever.

2. Since its first appearance there has been a rapid increase in the number of cases, and this increase still continues.

3. The causal organism has not yet been isolated but it is of the nature of a filterable virus.

4. Many cases are very gradual in onset and of a chronic nature throughout, and in these the acute stage is either absent or is so mild as to pass unnoticed even by the patient.

5. There has been a very marked change in type, the initial "negative" phase in which lethargy and palsies predominated being replaced by a "positive" phase with insomnia and involuntary movements as prominent symptoms and lethargy slight or absent.

6. The symptoms vary widely in different cases and many are liable to be missed unless a careful lookout is kept for the disease.

7. No drug has yet been discovered which has any permanent effect on the course of the disease.

8. The prognosis of Parkinsonism is very uncertain but it may remain practically stationary for at least seven years.

9. In some cases of Parkinsonism great improvement follows the use of hyoscine or belladonna, but this improvement is only temporary and the drug loses its power after a time.