Elsevier

Brain and Development

Volume 29, Issue 8, September 2007, Pages 486-490
Brain and Development

Original article
Autism and epilepsy: A retrospective follow-up study

https://doi.org/10.1016/j.braindev.2006.12.012Get rights and content

Abstract

So-called “idiopathic” autism, which exhibited no major complications before diagnosis is well-known as one of the risk factors for epilepsy. This retrospective follow-up study aimed to clarify the characteristics of epilepsy in the autism; onset of seizure, seizure types, EEG findings and epilepsy outcome and the differences as a group between the autism with epilepsy and those without epilepsy. One hundred thirty individuals with autistic disorder or atypical autism diagnosed in childhood were followed up over 10 years and were evaluated almost every year up to 18–35 years of age. Their medical records related to perinatal conditions, IQ, social maturity scores and several factors of epilepsy were reviewed in October 2005. Thirty-three of the follow-up group (25%) exhibited epileptic seizures. The onset of epilepsy was distributed from 8 to 26 years of age. Two types of seizure were observed; partial seizure with secondarily generalized seizure and generalized seizure. Twenty of the epileptics (61%) showed the partial seizure. Although 18% of the non-epileptic group exhibited epileptic discharges on EEG, 68% of the epileptic group revealed epileptiform EEG findings before the onset of epilepsy. No differences were observed concerning the sex ratio, autistic disorder/atypical autism and past history of febrile seizures between the epileptic and non-epileptic groups. Lower IQ, lower social maturity score and higher frequency of prescribed psychotropics were observed in the epileptic group compared to the non-epileptics. Idiopathic autism was confirmed as the high risk factor for epilepsy. Epileptiform EEG findings predict subsequent onset of epileptic seizures in adolescence. Epilepsy is one of negative factors on cognitive, adaptive and behavioral/emotional outcomes for individuals with autism.

Introduction

Many studies [1], [2], [3], [4], [5], [6], [7], [8] have pointed out a close relationship between autism and epilepsy. The reported rate of epilepsy in autism has varied from 12.6% to 39.2%. Since autism is defined by a particular behavioral phenotype, not by specific etiology or pathophysiology, all the studies mentioned above included individuals with “symptomatic” or secondary autism, i.e., West syndrome, tuberous sclerosis, fragile-X syndrome that had already exhibited epileptic seizures before the diagnosis of autism.

So-called idiopathic or primary autism, which exhibited no major complications before the diagnosis, is also well-known as one of the risk factors for epilepsy. This retrospective follow-up study aimed to clarify the characteristics of epilepsy in idiopathic autism, i.e., onset of seizure, seizure types, EEG findings and epilepsy outcome, and the differences as a group between autism with and without epilepsy.

Section snippets

Methods

The subjects of this study consisted of children referred to the Kanagawa Day Treatment & Guidance Center for Children for the evaluation of development, diagnosis and treatment of challenging behaviors. The author, one of the child neurologists at the center, checked up all subjects in the ordinary clinical setting and followed up almost every year from their first visit to adulthood. These subjects were selected from those individuals re-diagnosed by the author as having one of pervasive

Results

The subjects of this study consisted of 130 individuals with autistic disorder or atypical autism diagnosed in childhood (males, 104; females, 26). Their first visits ranged from 1 to 14 years of age (Median = 4 years). All but four subjects were followed up over 10 years by the author from their first visit. The median age of the subjects was 21 years (range: 18–35) at the time of this review.

Thirty-three out of the 130 patients (25%) developed epilepsy during the follow-up period. The

Discussion

This study has three unique points: first, the study focused on the relationship between “idiopathic” autism and epilepsy, second, this is the longest and largest retrospective follow-up study ever performed, and third, this study based on a huge number of routine EEG records (1165 records) obtained during the follow-up period.

The reported incidence of epilepsy in autistic individuals has varied from 13% to 40%. The occurrence of epilepsy in this study is 25%, which appears to be relatively

Acknowledgment

This paper was presented in the 10th International Child Neurology Congress, Montreal, Quebec, in June 2006.

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