Objectives: The aims of this study were to describe the prevalence of epilepsy and epileptiform EEG abnormalities in our group of ASD patients, to identify possible risk factors associated to the development of epilepsy in these patients, and to describe their management.
Methods: Two hundred patients diagnosed with ASD according to Diagnostic and Statistical manual of Mental Disorders of the American Psychiatric Association 4th edition (DSM IV) criteria in Hospital General Universitario Gregorio Marañon, from April 2010 to February 2011 were enrolled in this study. A retrospective chart review was done. Epidemiologic data was collected as well as data on past medical history, family medical history, neurodevelopment, neurological examination, presence or absence of seizures or epilepsy and the treatment given in each case, neuropsychologic evaluation, and EEG reports including sleep and wakefulness periods.
Results: The mean age of the group subjects was 7 years (range 17 month–16 years), 82% of the sample were male. Epilepsy was found in 14,5% of the subjects. The mean age at epilepsy onset was 48 months. Wakefulness EEG trace records were obtained in 181 patients (90%), abnormalities were found in 37 of them (18.5 %), most of them epileptiform discharges.
89% of the sample had idiopathic ASD and 11% had secondary ASD. Among the patients with idiopathic ASD 11,3% showed epilepsy. This percentage increased in patients with syndromic autism (40,9%).
52% of the sample showed different degrees of mental retardation (MR).
Epilepsy was more frequent in patients with mental retardation (15%) than in patients without mental retardation (12.5%), though this difference was not statistically significant (p=0.106). EEG abnormalities were found in 21.6% of patients with MR and in 17.7% without MR. There was no significant association between EEG abnormalities and mental functioning (p=0,565)
A history of language regression was reported in 31% of the patients, at a mean age of 18 months. Epilepsy was similar in patients with autistic regression (14%) as in non-regression patients (14.5%) (p=1,000).
16% of patients in the sample received treatment with antiepileptic drugs (AEDs). Of those who received treatment for the associated epilepsy, 66% did so as monotherapy and 33% in combination. The most commonly used AED was valproic acid alone.
Conclusions: The prevalence of epilepsy and EEG abnormalities observed in our sample
is at the lower limit of ranges reported in the literature, probably due to the characteristics of our sample, which had high percentage of idiopathic ASD. The prevalence is higher in patients with MR, syndromic autism and in females, the latter two reaching a statistically significant association. We conclude from our study that epilepsy is a comorbid factor of ASD and is not related to its pathogenesis.