Ictal EEG in patients with autistic spectrum disorder and epilepsy

Autism spectrum disorder (ASD) is a neurodevelopmental disorder frequently associated with epilepsy and epilepsy is a leading cause of death in ASD patients. Despite growing interest in genetic, neurophysiological and clinical overlaps, data on ictal electroencephalographic (EEG) recordings in ASD are lacking since behavioral disorders often make it difficult to obtain EEG recordings. We examined ictal EEG features in a consecutive series of patients with ASD and epilepsy.

We retrospectively identified 400 consecutive patients with ASD and epilepsy at our Level 4 Epilepsy center between 2015 and 2019; 45 had at least one EEG-recorded seizure captured. Demographics, age of nonfebrile seizure onset, age of ASD diagnosis, language, magnetic resonance imagining findings, genetic testing and EEG studies were reviewed. Seizures were classified by semiologic and electrographic features. Ictal findings were analyzed.

A total of 497 seizures were captured in 45 patients: 20 patients with focal onset epilepsy had 126 seizures (median: 1, range: 1-30), 17 patients with generalized onset epilepsy had 88 seizures (median: 2, range: 1-15), 7 patients with Lennox-Gastaut syndrome had 270 seizures (median: 12, range: 1-74) and one patient had both right hemisphere focal and generalized onsets (12 focal, 1 generalized).

Our study is the first to analyze a large set of ictal data in patients with autism spectrum disorder, a population traditionally difficult to obtain ictal recordings. Our results confirm the diverse spectrum of seizure types and provide clinical-EEG correlates of seizures in ASD patients. Both focal-onset and generalized-onset seizures were recorded, confirming that ASD patients have higher rates of both focal and generalized epilepsy syndromes. Among patients with focal epilepsy, temporal and frontal onsets were frequent, suggesting the possibility of epilepsy surgery or brain stimulation. EEG to classify seizures and epilepsies is critical to determine therapeutic options and effort should be made to obtain EEGs in this heterogenous population.