High occurrence of perinatal risk factors and more severe impairments in children with postneonatal cerebral palsy in Norway.

Aim: To describe causal events, perinatal risk factors and clinical characteristics in children with postneonatal cerebral palsy (PNCP).

Methods: Population-based registry study of Norwegian children born 1999-2013. Prevalence, causal events and clinical characteristics of PNCP were described. The occurrence of perinatal risk factors for CP was compared with the general population.

Results: Among 1710 children with CP, 67 had PNCP (3.9%; 0.75 per 10,000 livebirths [95%CI: 0.59-0.96]). The prevalence of PNCP decreased during the study period. Leading causal events were cerebrovascular events (32.8%), head injuries/other accidents (22.4%), infections (19.4%) and hypoxic events (14.9%). Spastic hemiplegic (53.7%) or spastic quadriplegic/dyskinetic CP (31.3%) was more common in children with PNCP than non-PNCP (42.3% and 20.1%, respectively; p < 0.001). Children with PNCP had more severe motor and associated impairments. Perinatal risk factors for CP were more common in children with PNCP than in the general population.

Conclusion: The prevalence of PNCP among Norwegian children was low and decreasing. The main causes were cerebrovascular events and head injuries/other accidents. Although spastic hemiplegic CP was the dominating subtype, children with PNCP had more severe motor and associated impairments than children with non-PNCP, as well as a higher occurrence of perinatal risk factors than in the general population.