The heightened risk of epilepsy in cerebral palsy (CP) was recognized by Freud more than 100 years ago. 1 His descriptions of the characteristics of the seizures indicate his appreciation of their essentially symptomatic nature. Much more recently, the importance of epilepsy as an adverse factor for cognitive function in children with hemiplegic CP has been highlighted. 2 The possibility that subclinical seizure discharges may add to cognitive problems requires particular attention in any child whose abilities may be already impaired secondary to structural brain abnormalities. Nevertheless, it is important to recognize that the motor difficulties, and any intellectual disabilities, as well as complicating seizures, are likely to stem from the same underlying pathology.
EpidemiologyIn the general childhood population, the prevalence of epilepsy is between 3 and 6 per 1000. 3 Overall, epilepsy occurs in between 15 and 55% of children and adults with CP. 1,48 If learning disability* coexists, the risk to children with CP is much higher, rising to 71%. 4 Epilepsy is more common in some forms of CP than others. Although Paine 1 found children with tetra-or triplegic CP to be among the least likely to have epilepsy, other authors 4, 9, 10 showed at least 50%, and up to 94% 9 to be affected. In hemiplegic CP, at least one-third, and up to a half in some series, 1,4,6,11,12 have continuing seizures. With spastic or ataxic diplegia, the risk is somewhat lower at 16 to 27%. 4,6,10,13 With the exception of reports from Germany and Sweden, that show much higher frequencies, 10 epilepsy is noted to complicate dystonic/dyskinetic CP in about one-quarter of cases; 4, 6, 14 and seems to be only rarely associated with pure ataxic CP. 4, 14 Thus, those cerebral palsies with possibly the more cortical pathologies seem most likely to be complicated by epilepsy.
Predisposing factorsThese can be considered under three main headings: genetic factors and pre-, and perinatal events. In addition, postnatal causes of CP, such as non-accidental or accidental head injuries and postencephalitic states may also be associated with epilepsy. In CP, information on the role of inherited predisposition to epilepsy is sparse in unselected populations. Curatolo and colleagues selected patients with CP, partial epilepsies, and learning difficulties on the bases of either structural lesions demonstrable on neuroimaging, or the presence of conditions likely to be secondary to pre-or perinatal asphyxia. Of these patients, the surprisingly high figure of 73% of their first-degree relatives were found also to have epilepsy; when compared with control individuals, those patients with prenatal pathology were 22 times as likely, and those with later pathology 14.5 times as likely as control individuals to have affected first-degree relatives. 15 In a study involving patients who were attending a seizure clinic, epilepsy was noted in 16% of first-degree relatives of those with CP, and 8% of relatives of control individuals with epilepsy, but no physical disa...