Epilepsy in children with cerebral palsy

Determining the prognosis of epilepsy in children with cerebral palsy is difficult. It undoubtedly depends on the type of cerebral palsy, its cause, and severity.

No population-based studies reflecting lengthy follow-up are available. Most prognostic studies are case series that intermix many types of cerebral palsy and lead to the following essential conclusions:

1. The more severe the cerebral palsy, the more likely the child is to develop epilepsy, and seizures usually begin at an earlier age than in children without cerebral palsy.
2. The clinical course and ease of seizure control appear to be related to the severity of the cerebral palsy.
3. Fewer children with cerebral palsy are able to discontinue antiepileptic drugs (AEDs) than are children with epilepsy without cerebral palsy.

Discontinuation of AEDs in children with epilepsy only

Berg and Shinnar29 completed a meta-analysis of 25 AED discontinuation studies. The number of years that a patient had to be seizure-free before drug discontinuation was not addressed, but the standard of practice at the time when most studies were conducted required 2 to 5 seizure-free years. Most of the reviewed studies did not specifically indicate a diagnosis of cerebral palsy. Therefore, the authors were able to consider only the effect of a more ill-defined term, motor deficits. In general, the relapse rate for epilepsy patients after 2 years of medication cessation was 30%. For children with “motor deficits” (neurologic abnormality), however, the relative risk of relapse was 1.79 (confidence interval, 1.13–2.83), as compared to those whose epilepsy had an idiopathic cause (i.e., no neurologic or cognitive problems).

In a study of 97 consecutively evaluated children who had been seizure-free for 1 year, regardless of seizure type or cause, AEDs were withdrawn over 4 to 8 weeks.28 Overall, 39% experienced relapse within the next 24 months (mean follow-up, 32 months). For children with a significant neurologic abnormality (one that interfered with activities of daily living), the rate of recurrence was 51%, compared to 32% for those with no neurologic abnormality. Cerebral palsy was not specifically identified in this study, but more than 90% of children who were reported to be “neurologically abnormal” most likely had cerebral palsy.

In the same study, 59% of those with remote symptomatic epilepsy experienced recurrence of seizures, versus 34% of those with idiopathic etiology.

In a cohort of children with epilepsy in Nova Scotia, 383 children became seizure-free while taking AEDs for a long enough period that withdrawal of medication was attempted.30 Of the 293 without neurologic handicap, 90(31%) had recurrent seizures within 2 years. Of the 56 children with significant neurologic handicap, 30 (54%) had recurrent seizures, an appreciably higher proportion. Other studies31–33 have also found neurologic dysfunction to be an adverse risk factor for relapse.

Discontinuation of AEDs in children with epilepsy and cerebral palsy

Overall, children with cerebral palsy and epilepsy take longer than those without this dual handicap to achieve a seizure-free period of 1 to 2 years. The control of epilepsies associated with cerebral palsy is especially difficult when the lesions are large or related to syndromes such as West syndrome (infantile spasms) or Lennox-Gastaut syndrome. The child with cerebral palsy plus epilepsy who does become seizure-free for 1 to 2 years has a good chance of remaining seizure-free when medication is withdrawn, however.28 Seizure freedom will eventually be reached by 40% to 60% of these children.

Early studies, such as that of Roger and Bureau34 in 1982, found that 30% of patients with epilepsy and cerebral palsy entered long-term remission after 5 to 15 years of follow-up, as compared to 70% who had epilepsy only. Eventually, 50% had complete seizure control, with 60% off AEDs.

In another study, the Marseilles group described 97 children with severe cerebral palsy.35 The eventual outcome, good or bad, was known within the first 3 years of life. By 14 years of age, 40% were seizure-free, half without medication.

Asku10 was able to discontinue AEDs in 40% of 174 children who were seizure-free for at least 2 years. Sillanpaa et al.36 followed through 1992 a cohort of 245 children with active epilepsy in 1961–1964. Of those with remote symptomatic epilepsy, 45% were in remission, and 24% had stopped all medication.

Although following somewhat different procedures, other investigators have also found that a significant percentage of children with this dual handicap eventually become seizure-free and can discontinue the use of AEDs. In study by Delgado and colleagues,37 AEDs were discontinued in children with epilepsy and cerebral palsy after 2 seizure-free years. During the next 2 years, 42% of those with spastic cerebral palsy experienced relapses. Those with hemiparesis had the highest relapse rate (62%), whereas those with diplegia had the lowest (14%).

In the study by Zafeiriou et al.,27 AEDs were discontinued after 3 seizure-free years. Only 18 of 134 patients experienced relapse over a follow-up period of 5.8 ± 1.2 years. Of the 18 with recurrence, 11 (61%) had hemiplegic cerebral palsy, 4 (22%) had dystonic cerebral palsy, and 3 (16%) had diplegia. These numbers are surprisingly low and may reflect a small sample or referral bias.

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).

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