Epilepsy is one of the disorders most commonly associated with cerebral palsy (CP). Studies reporting the frequency of epilepsy in children with CP describe the coexistence of the two disorders in up to 50% of children. The reported frequency varies widely (more than for mental retardation [MR]) because different sources of information are used and because of the great clinical heterogeneity of CP. Some of the studies dealing with the risk of epilepsy in children with both MR and CP were reviewed in the page on children with MR. The rest of this page focuses on studies that emphasize children with CP.

Population-based studies

Rochester, Minnesota

The feasibility of identifying all cases of a given disorder over several decades makes the population of Rochester, Minnesota, ideal for many epidemiologic studies. Kudrjavcev et al.30 identified 63 individuals born in Rochester between 1950 and 1976 in whom CP had been diagnosed before their 16th birthday. The authors classified patients by CP severity, based on the function of the most affected limb and, in most cases, by the ability to walk. Patients were divided into two groups:

  • mild CP (able to walk without marked difficulty in the absence of any mechanical aids) to moderate CP (ambulated with difficulty but required no mechanical assistance)
  • severe to very severe CP (able to walk only with the assistance of mechanical aids, and the function of the most affected limb was completely lost even in the presence of mechanical aids)

The authors investigated the presence of associated handicaps (MR and epilepsy). Epilepsy was defined as two or more afebrile seizures occurring after 28 days of life.

Overall, 33% of the children in this study had epilepsy:

CP severity Proportion with epilepsy
Mild to moderate 23%
Severe to very severe 52%

More than 65% of patients with severe to very severe CP had an IQ of 35 or less, as compared to 5% of those with mild to moderate CP. None of the children with mild to moderate MR or with severe CP and normal intelligence had epilepsy.

Because more than half of those with severe to very severe CP had epilepsy, we can assume that epilepsy was more common in children with CP when accompanying MR was severe as compared to mild to moderate.

Clinical series

Sussova et al.31 investigated the frequency of epilepsy in children with the hemiparetic form of CP who were seen at a Prague pediatric neurology center or were registered to an institute caring for all “educable” children with CP. Of the children included in the study, 37% developed epilepsy. However, this study is characterized by several limitations. Children were highly selected owing to the source used for case ascertainment: Children considered totally uneducable were excluded. As a result of such restriction, only 3 of the 51 children involved had an IQ of less than 85. No clear definition of epilepsy was given. The authors’ conclusion that “epilepsy was significantly associated with the probability of intellectual impairment” likely is correct, although their study does not address the question. No children with MR (according to usual definitions) were included in the study: Children were considered intellectually impaired if the IQ was no higher than 94. According to this definition, 63% of the children with epilepsy had an abnormal IQ.

Mrabet et al.32 determined the frequency of epilepsy in children with CP who were admitted to a specialized center for rehabilitation. Only children with mild forms of MR (IQ, 60–80) were registered to the center. Overall, 26% of children with CP had epilepsy. Moderate to severe MR was significantly more frequent in children with epilepsy and CP (38.8%) than in those with CP and no epilepsy (17.6%).

When children with more severe MR are included, higher rates of epilepsy are reported in children with CP. One study looked at children who were inpatients or outpatients of a pediatric department or outpatients of four rehabilitation centers in Athens. Epilepsy (defined as the occurrence of at least two unprovoked seizures) was present in 42% of children with CP.33 Patients with moderate to severe MR (IQ <50) had more than a twofold increased risk of developing epilepsy when compared to patients with normal IQ level (IQ >70). The identification of children from physiotherapy and rehabilitation programs suggests that milder forms of CP probably were not included in the study. This might explain the high proportion of epilepsy found in the study.

Of all children with CP registered to a university referral center (Department of Developmental Medicine and Child Neurology), 36% had concomitant epilepsy,34 defined as the occurrence of two or more unprovoked seizures. MR (IQ <70) was significantly more common in children with CP and epilepsy (54.5%) than in those with CP alone (32.4%).

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). 

Reviewed By: 
Steven C. Schachter, MD
Saturday, May 1, 2004