The epidemiology of cerebral palsy: incidence, impairments and risk factors.

PURPOSE: Describing the epidemiology of cerebral palsy (CP), its impairments and risk factors.

METHOD: Literature review 1965-2004. Search terms: Cerebral palsy, incidence, prevalence, impairments, risk factors.

RESULTS: In the last 40 years the prevalence of CP has risen to well above 2.0 per 1000 life births. In this time span the proportion of low-birthweight infants rose, the proportion of diplegia decreased, while the proportion of hemiplegia increased. CP is more prevalent in more deprived socio-economic populations. The majority of people with CP have the spastic syndrome of which the diplegic group is the smallest. Dependent on the subgroup of CP, 25-80% have additional impairments. A large proportion has some kind of cognitive impairment; the prevalence varies with the type of CP and especially increases when epilepsy is present. Epilepsy is present in 20-40%; it is most common among the hemi- and tetraplegics. Sensibility of the hands is impaired in about half. Chronic pain is reported by more than a quarter of the adults. Up to 80% have at least some impairment of speech. Low visual acuity is reported in almost three-quarters of all children. Half of all children have gastrointestinal and feeding problems. Stunted growth occurs in a quarter, while under- or overweight problems are present in half of the children. Almost 70% of people with spastic CP have abnormal brain CT findings; abnormal cranial ultrasounds is most strongly associated with hemiplegia, normal cranial ultrasounds with diplegia. The most important risk factors for CP are low birthweight, intrauterine infections and multiple gestation.