Clinical aspects of cerebral palsy in Iceland: A population-based study of preschool children

Abstract

Cerebral palsy (CP) is the most common motor impairment of childhood, affecting approximately 2 children per 1000 live births.1 Unfortunately, the rate in most areas has not changed during recent decades; therefore the burden imposed by CP on society has not abated despite relevant advances in medical care.2 As CP is caused by injury to the developing brain it is multifaceted in nature and affects not only the child’s motor development and capacity but also cognition and communicative ability as well as mental health. CP was studied quite extensively in Iceland as early as the 1960s3 but since then it has not been a subject of research in Iceland. Therefore, the aim of my thesis is to assess the prevalence and associated impairments related to the higher cognitive functions of a total population of preschool children affected by congenital CP.

The prevalence of CP did not change between the study periods; it was 2.2 per 1000 live births among children born from 1990 to 1996 and 2.3 among children born from 1997 to 2003. However, among term births the prevalence and severity of CP decreased. Almost half (42%) of the group had normal cognition whereas 40% had intellectual disability. The median verbal intelligence quotient (IQ) was higher than the performance IQ for the whole group and children with diplegia and quadriplegia had distinct weaknesses within the visual reasoning domain.

Children with CP were three to four times more likely to show considerable psychological symptoms on parental assessment than the comparison group and the risk was even higher when rated by preschool teachers. Attention problems and being withdrawn were the most problematic symptoms across situations. Most children could express themselves in sentences (72%); two-thirds had normal speech or mild dysarthria, whereas 16% were non-verbal. Almost half of the total group had verbal intelligence scores in the normal range. Nonverbal status and severe dysarthria were associated with intellectual disability, greater motor impairment and the quadriplegic and dyskinetic subtypes.

When the results are compared with the previous study on CP in Iceland3 we observe that the prevalence of CP was the same in the middle of the 20th century as it was at the turn of the century, whereas the rate among full term children decreased from 3.7 to 1.2 cases per 1000 live births (p<0.001). The proportions of children with intellectual disability and hearing impairment decreased and evidence suggests a decrease in the motor impairment over time. Thus the overall impairment associated with CP among Icelandic children has decreased during recent decades.

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