Influence of gestational age on nosologic CP characteristics in a high-risk population.

The aim of this study is to investigate the interrelationship between gestational age (GA) and nosologic characteristics (type, distribution and severity) of cerebral palsy (CP) in a cohort of high-risk infants. One thousand ninety-nine consecutively neonatal intensive care unit-admitted high-risk infants (i.e., all infants with a GA less than 30 weeks and specified infants with GA >or= 30 weeks with a complicated neonatal course and/or brain lesion) were prospectively assessed up to the corrected age of 2 years or more. In 177 (16%) of these infants, CP was diagnosed. Of these infants, 26 were extremely preterm infants (GA 23-27 weeks), 62 very preterm (28-31 weeks), 36 moderately preterm (32-36) and 53 term infants (GA >or= 37 weeks). Spastic CP was significantly more present in the three preterm groups (77%, 90% and 72%, respectively) compared with the term ones (42%). At variance, dyskinetic CP was present in nearly half of the term group (47%) and remarkably less in all three preterm age groups (12%, 7% and 22%, respectively). Ataxic CP (7%) was of rare occurrence in all age groups. Distributive classification showed that bilateral spastic CP gradually dropped from 100% in the extremely preterm group down to 50% in the term infants. Inversely, unilateral spastic CP rises steeply with advancing GA. Severity of CP was significantly associated with birth year period in favour of mild CP. In high-risk neonates, dyskinetic CP increases steeply with increasing GA, whereas spastic CP decreases. Bilateral and unilateral involvements are gradually and oppositely changing with gestational age. It is tempting to explain the maturity-related association by gestational age-specific brain injuries.