Abstracts

Rationale: There is a frequent association between epilepsy and autism spectrum disorder (ASD), particularly among pediatric patients; the prevalence of epilepsy in autism has been estimated as high as 30% in children, and has been found to be much larger than in the general population, where less than 1% will have epileptic seizures by the age of 20 years. We hypothesized that sleep EEG patterns in autism would share strong similarities with those observed in epilepsy.Methods: 205 patients were included in this retrospective study (126 Mand 79 F), age <19 years old. All patients underwent a V-EEG evaluation at the UH Rainbow Babies’ EMU between 2009-2014. Data of those patients was reviewed and classified into four groups based on diagnoses: patients with autism spectrum disorder and no history of epilepsy (Group A, n=26); patients with epilepsy but no history of autism (Group E, n=43); patients with epilepsy and autism spectrum disorder (Group A/E, n=55); patients with normal V-EEG (controls) and no history of autism or epilepsy (Group N, n=57). We analyzed patient histories as well as the awake and sleep EEG recordings, including: the posterior dominant rhythm, sleep structures, non-epileptiform and epileptiform abnormalities, and the frequency and morphology of the interictal discharges. Differences between groups were evaluated with cross-tabulation techniques.Results: Regarding the posterior dominant rhythm (PDR): A slow PDR was observed in 3% of Group E and 16.4% of Group A/E. No PDR was recorded in 1.8% of Group N, 3.8% of Group A, 3% of Group E and 7.3% of Group A/E. Regarding the sleep spindles: Non-intact spindles were observed in 5.3% of Group N, 7.7% of Group A, 44.8% of Group E and 41.8% of Group A/E. Spindles were asymmetric 3% of the Group E and 1.8% of the patients of Group A/E. We observed a focal intermittent slow pattern in 1.8% of Group N, 3.8% of Group A, 3% of Group E and 10.2% of Group A/E. Generalized intermittent slow pattern was observed in a 1.8% of Group N, 3.8% of Group A, 7.5% of Group E and 12.7% of Group A/E. Generalized continuous slow pattern was observed in 3.8% of group A, 10.4% of group E and 9.1% of group A/E. Only 1.8% of Group N showed an asymmetric beta discharge. Focal epileptiform activity was observed in 3.5% of Group N, 15.4% of Group A, 37.2% of Group E and 47.3% of the Group A/E. Generalized epileptiform activity was observed in 1.8% of Group N, 3.8% of Group A, 91% of Group E and 61.8% of Group A/E.Conclusions: There is a significant increase in the amount of the interictal discharges in the autism patients, even in the absence of epilepsy: 19.2% vs 5.3% of our control group. However, patients with autism as a whole had a lower prevalence of non-intact spindles during sleep in comparison to patients with epilepsy. We also observed a slower PDR in patients with autism and epilepsy in comparison to the patients with epilepsy alone (16.4% vs 3%). We are now investigating possible physiological mechanisms associated with these abnormalities, as well as looking further into their sleep morphology.