"Cerebral palsy" is a term of convenience applied to a heterogeneous group of nonprogressive motor disorders of central origin covering a wide range of cerebral dysfunctions occurring early in life.12 Often included in the case-finding method is an age of at least 3 years, as the diagnosis of cerebral palsy is occasionally difficult at younger ages.

Incidence

Population-based data delineating the incidence of cerebral palsy are available from numerous large, longitudinal registers.1,13–16 These registers yield incidence figures of approximately 2.5 cases per 1,000 live births (Figure 1).

Incidence of cerebral palsy per 1,000 live births from population-based registers from the United Kingdom, Sweden, and western Australia, 1959-1992. Note that data for the Mersey region of the United Kingdom are for 1967-1989 only; Swedish data are to 1990 only. Rates exclude cerebral palsy due to postneonatal causes.

British registers show higher rates of cerebral palsy than western Australian registers:17,18

The Swedish register reports a comparable rate of 2.5 per 1,000 live births among singletons in 1993.15

Etiology

The etiology of cerebral palsy is thought to be multifactorial and is incompletely understood. Early descriptions indicated that birth injury was responsible, giving rise to a whole generation of pregnancy and delivery interventions. Despite these interventions, the incidence of cerebral palsy has not declined, and recent information indicates that only 2–10% of cases are caused by intrapartum hypoxia.8,19,20 A small additional percentage (perhaps 15%) may be the result of postneonatal difficulties.

Evidence therefore favors a prepartum origin for most cases of cerebral palsy. Poor intrauterine growth is an important risk factor for cerebral palsy in infants with a gestational age greater than 33 weeks.21 Approximately 40% of infants who develop cerebral palsy weigh less than 2,500 g at birth, and one study of spastic cerebral palsy found nearly 50% of these infants to have associated prenatal factors, as compared with about 20% of those infants weighing more than 2,500g.

Overall, however, 50% of cerebral palsy patients were shown not to have experienced any prenatal, perinatal, or neonatal factors.22 Further in-depth studies are needed to elucidate causal pathways to cerebral palsy.

Types

The predominant types of cerebral palsy identified in 756 children within the western Australia registry(1975–1990) 14 were:

• hemiplegia (36%)
• diplegia (32%)
• quadriplegia (16%)
• extrapyramidal (ataxia, hypotonia, and dyskinesia) (16%)

A marked increase in the number of children with quadriplegia and extrapyramidal cerebral palsy has been noted in this register since 1975. This may be due to the increased survival of low-birth-weight and premature infants or, perhaps, better recognition of extrapyramidal cerebral palsy. Other registers have similar information.

Adapted from: Camfield CS, Camfield PR, Watson L. Cerebral palsy in children with epilepsy. In: Devinsky O and Westbrook LE, eds. Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;33–40. With permission from Elsevier (www.elsevier.com).

Reviewed and revised May 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.

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