The dual handicap

Incidence

The population-based study in Goteberg, Sweden by Hagberg et al.15 found that 28% of people with cerebral palsy also had epilepsy. An update of this study published in 2003 reported that 38% (55/146) developed epilepsy by 6 to 14 years of age.40 Similarly, the Danish Cerebral Palsy Register reported that 27.1% of patients born with cerebral palsy between 1979 and 1986 also had epilepsy.16 Data from western Australia from 1975 through 1994 record the incidence rate of epilepsy to be 37% (618 of 1,664).14 The type of seizure associated with each type of cerebral palsy is not described within these registers.

The rate of combined epilepsy and cerebral palsy of 0.8 per 1,000 live births has remained constant over 25 years. With improvements in neonatal care during the last 20 years, the number of surviving premature and low-birth-weight babies has increased, with a concomitant increase in the rate of cerebral palsy.

Severity of cerebral palsy

Children severely affected by cerebral palsy seem to be more likely to develop epilepsy. This aspect was studied in Rochester, Minnesota, between 1950 and 1976, when 64 cases of cerebral palsy were identified.23 Of patients with severe cerebral palsy (defined as function limited to mechanical aids and characterized by marked difficulty) 52% also developed epilepsy. Conversely, epilepsy was present in 23% of those with mild to moderate cerebral palsy. Although the sample is small and spans the years before modern prenatal care, more recent data from western Australia support these findings. Watson and Stanley (personal communication) found that 65% of children with severe cerebral palsy born between 1975 and 1994 developed epilepsy, as compared with 24% of children with minimal, mild, or moderate cases of cerebral palsy.

A history of neonatal seizures is frequently found in children with the dual pathology of both epilepsy and cerebral palsy. Kwong26 found this association in 19% and Carlsson40 found it in 24% (23/55). Most of the children’s seizures were thought to be of prenatal origin.

Type of cerebral palsy

The frequency of occurrence of epilepsy varies according to cerebral palsy type:

Aicardi24 combined data from several studies. Carlsson’s study40 is population-based. Hadjipanaysis et al.25 studied a clinic-based group of 323 children from Greece with cerebral palsy, and found that overall, 41.8% had epilepsy. As shown above, Kwong et al.26 in Hong Kong also found very different epilepsy frequency statistics among 32 children with these dual handicaps, depending on the type of cerebral palsy present.

Referral and diagnostic criteria for all these studies differed, and all had small sample sizes. Therefore, the studies are unlikely to represent the true incidence of epilepsy according to cerebral palsy type. Nonetheless, it is generally believed that patients with quadriplegia and hemiplegia develop epilepsy more often than do those with diplegia. Extrapyramidal cerebral palsy has had the lowest rate of associated epilepsy, probably about 10–15%.

Age at onset

Age at onset of the epilepsy has a close relationship with the type of cerebral palsy:26

Similar results were described from a Greek referral center27 following up 178 children with epilepsy and cerebral palsy: The prevalence of epilepsy in this clinic was 36%, and the onset of seizures occurred in the first year of life in 73% of the children. Carlsson40 in Sweden found that 91% had developed epilepsy by 6 years of age. It appears that earlier age of onset of epilepsy is correlated with an increased severity of cerebral palsy, and the story of whether or not a child with cerebral palsy will develop epilepsy is almost completely written by the age of 6 years.

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, and Carol Camfield, MD, epilepsy.com Editorial Board.

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