Clinical factors associated with epileptiform electroencephalographic and structural brain magnetic resonance imaging abnormalities in children with autism spectrum disorder

Aims: This study aimed to investigate the clinical correlates of epileptiform electroencephalographic (EEG) abnormalities and clinically significant structural brain magnetic resonance imaging (MRI) findings in children with autism spectrum disorder (ASD). Methods: This cross-sectional study included 218 children with ASD who were evaluated at both the child neurology and child and adolescent psychiatry clinics. Demographic and developmental characteristics, ASD severity, developmental regression, intellectual disability/developmental delay, clinical epilepsy, neurological examination findings, EEG recordings, and brain MRI findings were assessed. Multivariable logistic regression analyses were performed to identify factors independently associated with epileptiform EEG and clinically significant MRI abnormalities. Results: EEG recordings were available for 174 patients, of whom 52 (29.9%) had epileptiform abnormalities. The frequency of epileptiform activity increased with ASD severity. Severe ASD (adjusted odds ratio [aOR]=2.61), developmental regression (aOR=2.38), clinical epilepsy (aOR=4.72), and increasing age (aOR=1.08 per year) were independently associated with epileptiform abnormalities. Severe ASD and developmental regression remained significant after exclusion of children with clinical epilepsy. Brain MRI was available for 146 patients; 26 (17.8%) had clinically significant structural abnormalities. Abnormal neurological examination (aOR=5.86) and developmental regression (aOR=2.54) independently predicted significant MRI abnormalities, whereas ASD severity and epileptiform EEG did not. Conclusion: Epileptiform EEG and clinically significant MRI abnormalities showed distinct clinical correlates in children with ASD. Developmental regression was associated with both outcomes, whereas severe ASD was associated primarily with epileptiform activity and abnormal neurological examination with structural MRI abnormalities. These findings support a phenotype-informed approach to neurological evaluation in ASD.