View report page

22
prevalence of cerebrospinal fever in 1915 and of poliomyelitis in 1916 and was
succeeded bv the encephalitis prevalences of 1921 and 1924.

The relationship
of
influenza
to epidemic
diseases
affecting the
central nervous
system.
Some of the problems associated with these diseases were considered in a special
report of 1918 and in later annual reports; they have assumed prominence during the
past year owing to the persistently maintained though not very extensive prevalence
of influenza, and to the fact that with comparatively little increase in the other
epidemic diseases of the nervous system there was developed the quite unexpected
rise in "encephalitis lethargica" which has been above referred to. This latter
phenomenon must first be considered in connection with its bearing upon the
general question of the relationship between the various diseases of the influenza
group.
The types of
epidemic
disease of
the central
nervous
system asso
ciated with
influenza
prevalences
during the
last seven
years.
The disease, which is still known in this country by the (as it now appears)
not altogether appropriate name given to it, in Vienna in 1917, has proved in recent
years in widely separated parts of the world to differ so strikingly from the earlier
descriptions, of the outbreaks in France and Vienna, as pointedly to challenge attention.
When the prevalence was first spoken of as "encephalitis lethargica"
seven years ago it was held to be especially characterised by lethargy and ocular
palsies. Students of the history of epidemics who had so often heard of "new
diseases" before, urged that this disease was not new, "Hie morbus non est novus,"
in the time-honoured phrase which Crookshank has exhumed from the middle of
the eighteenth century and brought once more into the light of day. The possibility
suggested itself, quite at the outset, that the prevalence constituted one of the phases
of influenza; for the most unfailing clue, as has been remarked, to the discovery
of "influenza in mufti" is just this fact that, revolving as they do in a cycle of twenty
or thirty years, the influenzal group of diseases present phases which are new in the
experience of any particular generation of sufferers.
The two striking symptoms of the "encephalitis lethargica" of 1917 have,
in various places, both here and in America, in the last four years, tended to be overshadowed—lethargy
by insomnia or by altered sleep rhythm, and muscular palsies
by myoclonic contractions (see Ann. Eep. for 1923, p. 25). Dr. J. C. Spence
stated (Lancet, 7th February, 1925) that "the old oculo-lethargic type of case no
longer occurred, in the spring of 1924 in Newcastle, but was replaced by an acute
painful myoclonic type, with difficulty diagnosed from acute rheumatism or an
acute abdomen." The myoclonic cases may have been present earlier, however,
at any rate in London. In the annual report for 1922 (p. 65) cases of chorea, occurring
in East London between 1919 and 1923, are discussed by Dr. Chaikin, and some of
these cases of "chorea" may have been due to encephalitis. Dr. Hall, speaking of
Sheffield, says: "with each recurrence of the epidemic, symptoms became prominent
which in previous waves had only been occasional or temporary, thus necessitating
the creation of a new group into which they could be fitted" . . . After referring
to the appearance of myoclonic contractions in 1920, he adds, "It thus became
almost necessary to create a new type for each case, and even then a single case in
its course went through so many types that its classification became almost im-,
possible." He points out, moreover, that Pecori in Italy made out thirteen forms,
"whilst a combination of any two or three of these may become a separate form in