..

Cerebral Palsy Epidemi oI ogy:

Where are We Now and Where are We Going? OVER the past decade, regular international meetings devoted to the state of the art in the epidemiology of cerebral palsy have been held: in California in 1987, in Cambridge in 1989 and in Brioni, Yugoslavia, in 1990. Among the longstanding problems considered have been those of case definition, case-finding, reported changes in prevalence, the bases on which distinctions between different clinical types and meaningful classification can be achieved, and the crucial question of the timing and nature of the original insult. Reports of the meetings have not been published, however, so this annotation is intended to document some of the recurrent questions that have been considered.

Prevalence There have been consistent reports of recent rises in the prevalence among live births of the condition and its severity, particularly among preterm infants’.

These rises seem to be accounted for largely by improvements in survival rate, since the incidence rates of low birthweight and the birthweight-specific prevalence rates of cerebral palsy among births of 2500g or more seem to be remaining largely stable’. Table I shows published and unpublished data for birthweight distribution, mortality and cerebral palsy rates from registers in three different places. The figures from the most recent period probably should be regarded as provisional. The consistent trend in all countries from low to high cerebral palsy rates as birthweight falls is clearly shown, and within countries in the low-birthweight populations there is a trend to higher rates as mortality falls. The birthweight-specific prevalence of cerebral palsy in the highest weight-group seems to remain largely stable within each population, despite falling mortality levels. The effect of increased survival is linked closely with the timing of the causal insult, and yet we still do not know the relative importance of prenatal and perinatal factors in the aetiology of cerebral p a l s ~ ~Prenatal -~. damage may lead to a preterm or difficult delivery, which may be misinterpreted as causal. Where the initial cause predated the delivery, increased survival can only lead to an increase in birth prevalence. However, for those who are potentially normal at birth,

rn ‘A ‘A

t‘A d

d-

m

$! Q‘

5 e

2

$ 2

3 2 -\

.s* $

s

-5

%

B

2 2

4

547

L

w

-

TABLE I International comparisons of cerebral palsy rates per 1000 neonatal survivors: perinatal mortality rates (PNM) and birthweight distribution

4

Birth weight'(g)

C

.-m

I

0

1975 to 1978

PNM % LB* CP/100088 PNM

*

Sweden < 1500 1500-2499 2 2500 W.Australia < 1500 1500-2499 2 2500 Mersey

Cerebral palsy epidemiology: where are we now and where are we going?

Cerebral Palsy Epidemi oI ogy: Where are We Now and Where are We Going? OVER the past decade, regular international meetings devoted to the state...
393KB Sizes 0 Downloads 0 Views