Epidemiology of cerebral palsy

Cerebral palsy (CP) is defined as a chronic, nonprogressive cerebral disorder in young children that results in impaired motor function.17

Classification

Cerebral palsy is classified according to the nature of symptoms (spastic, extrapyramidal, mixed) or the distribution of maximal disability:

  • diplegia, 10–33% of cases
  • quadriplegia, 9–43% of cases

Description of severity also can be part of the classification.

Prevalence

Despite variability in methods, most studies indicate a prevalence of 1.2 to 2.5 per 1,000 children of early school age.14

Risk factors

In the past, traumatic delivery was considered a risk factor for CP, but systematic studies fail to show a high correlation with this adverse event.14,15,18,19 In population-based studies, most cases of CP (80%) show no clinical evidence of birth asphyxia or other adverse events.14,15,18-20,

Low birth weight and reduced gestational age at birth are conditions considered to be associated with a high risk for CP. Progress made in neonatal critical care has improved survival of children with these characteristics, and so these children now constitute a large and increasing fraction of all CP cases.

Three other factors that contribute to the risk of CP, regardless of birth weight, include congenital malformations, inflammation of the placenta, and twinning.

A nonspecific association exists between spastic quadriparesis with movement disorder and birth asphyxia. Although motor dysfunction is the defining characteristic in patients with CP, the disorder often is associated with other problems, including epilepsy and MR.

CP has been attributed to intrauterine toxic exposures (methyl mercury, exogenous thyroid hormone, and estrogens) and intrauterine infections (rubella, toxoplasmosis, and cytomegalovirus).

Adapted from: D'Amelio M, Shinnar S, and Hauser WA. Epilepsy in children with mental retardation and cerebral palsy. In: Devinsky O and Westbrook LE, eds. Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;3–16.
With permission from Elsevier (www.elsevier.com). 

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