Elsevier

The Lancet Neurology

Volume 1, Issue 6, October 2002, Pages 352-358
The Lancet Neurology

Review
Epilepsy in autism

https://doi.org/10.1016/S1474-4422(02)00160-6Get rights and content

Summary

There is an increased but variable risk of epilepsy in autism. Three main factors—age, cognitive level, and type of language disorder—account for variability in the reported prevalence of epilepsy. The prevalence is highest in studies that have included adolescents and young adults, individuals with moderate to severe mental retardation and those with motor deficits, and individuals with severe receptive language deficits. The association of autism with clinical or subclinical epilepsy might denote common genetic factors in some cases. Whether subclinical epilepsy has adverse effects on cognition, language, and behaviour is debated, as is the relation of autistic regression with an epileptiform electroencephalogram to Landau-Kleffner syndrome. There is no evidence-based treatment recommendation for individuals with autism, regression, and subclinical epilepsy. Double-blind studies with sufficient power to resolve this issue are urgently needed.

Section snippets

Aetiology and pathophysiology of autisticspectrum disorders in relation to epilepsy

Non-genetic and diagnosable genetic disorders account for no more than 10–20% of individuals with autism.17, 18 Infrequently, autism may develop as a result of nongenetic, acquired damage to the immature brain that may or may not give rise to epilepsy.16 Although perinatal asphyxia, prematurity, adverse responses to immunisations, and other misadventures of gestation or postnatal life are often invoked, evidence that they are the cause of autism in the absence of more classic signs of brain

Epilepsy in autism: prevalence and risk factors

Reports of the frequency of epilepsy in autism range from 5% to 38·3%.9, 10, 41, 44, 45, 46, 47, 48 There seems to be a bimodal age distribution of seizures in autism. One peak occurs in infancy before age 5 years and the other in adolescence after age 10 years.47 Whether epilepsy in other developmental disorders has the same distribution is not known. The disparate prevalence of seizures among studies reflects different age populations studied, with the lowest rates in studies of children only,

Subclinical epilepsy: overlaps between disorders

The developing brain is well known to be more susceptible to seizures than the mature brain.51, 52 Some studies suggest that epileptiform discharges on electroencephalography (EEG) without clinical seizures can cause behavioural and cognitive impairment.53, 54 Some children who have benign partial epilepsy of childhood with rare seizures but very active centrotemporal epileptic EEG foci have shown cognitive impairment, although long-term data are still limited.55 The same may be true of

Autistic regression

The manifestations of autism change with age and in many cases improve with early intervention. However, about a third of parents report a regression of language, most commonly the loss of their toddler's first few words between the ages of 18 and 24 months,45 together with the appearance of autistic behaviours. In disintegrative disorder, language and behavioural regression is delayed and can occur as late as age 10 years.61 Autistic regression, including regression in language, is not

Receptive–expressive language disorder

In both autism and dysphasia, the language disorder subtype most likely to be associated with epilepsy is the most severe variant of the mixed receptive-expressive language subtype, verbal auditory agnosia,9 which is caused by temporal-lobe dysfunction,68 and is therefore particularly likely to be associated with seizures. Our study,9 which classified children with autism and dysphasia without moderate or severe mental retardation into four subgroups based on language subtype, found that

Epileptiform EEG

Long-duration EEGs that include an adequate sample of slow-wave sleep are significantly more likely to show epileptiform abnormalities than are routine 1 h recordings, at least in children with autism and a history of regression.9 Long-duration video-EEG telemetry studies of children with autistic-spectrum disorders and a history of regression but without clinical seizures disclosed an epileptiform EEG in 46%.73 The use of magnetoencephalography to map out the dipoles of epileptiform discharges

Surgical treatment

Surgical transection of epileptogenic frontotemporal cortex has been offered to small numbers of children with LKS, with short-term reports of improvement in language and behaviour in perhaps 50% of those treated.93, 94 A few studies of children with autistic regression and clinical seizures found that aggressive treatment with epilepsy surgery is associated with positive outcomes.95, 96 We emphasise that the children in these case reports had intractable epilepsy and that the surgery was being

Conclusion

The relation of clinical and subclinical epilepsy to autistic behavioural and language regression and to disintegrative disorder is intriguing but unresolved. The present evidence suggests that there are common pathophysiological mechanisms that account for both the autism and the epilepsy. There is a compelling need to identify specific biological subgroups within the broader autistic spectrum to strengthen our understanding of the genetics of some of the behavioural components of autism and

Search strategy and selection criteria

Data for this review were identified by searches of Medline with the terms “autism”, “pervasive developmental disorder”, “regression”, “seizures”, and “epilepsy”; also from the authors' files, and from relevant references. Abstracts and reports from meetings were included only when they related directly to previously published work. Because the term autism did not appear until the 1980 third edition of the DSM100 assessment of papers that appeared before that time is difficult. In

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