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
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
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
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.