Abstracts

Rationale: Epilepsy and high rates of interictal electroencephalographic (EEG) discharges are commonly observed in children with autism spectrum disorders (ASD). Susceptibility for visually induced seizures can be predicted by provoking a photoparoxysmal response (PPR) with intermittent photic stimulation (IPS) during EEG recordings. The presence of a PPR is highly correlated with generalized, photosensitive epilepsy. Children with ASD frequently engage in self-stimulatory behaviors that can create a stimulus of flickering light, with the potential for inducing photosensitive seizures. For this reason, it is important to determine the rate at which children with ASD exhibit a PPR. This is a pilot study to retrospectively determine the incidence of PPRs elicited during EEG studies in children with ASD at Children s Hospital Boston.Methods: Children with a diagnosis of ASD receiving medical care at Children s Hospital Boston between 12/2010 and 4/2011 were identified through a search of electronic medical records. Of these children, those with an EEG study during or prior to the search period were included in the study. Data was obtained on demographics, including age, gender, and diagnoses of epilepsy. EEG reports were examined to determine the presence or absence of a PPR.Results: The search found 333 children with an ASD diagnosis with an EEG considered, and 206 who had an EEG study. The median age was 9 years (range 1-23 years), with 161 boys, 45 girls. There were 118 children with ASD and epilepsy, and 88 with ASD without seizures. IPS was done in 177/206 (86%) (138 boys, 39 girls), and a PPR was elicited in 13/177 (7.3%), 10/138 (7.2%) boys and 3/39 girls (7.7%), with no difference based on gender. Subdividing by age into 4 groups; Group 1 (n=53): 0-5 years, 2 (3.8%) children with PPR, Group 2 (n=63): 6-9 years, 3 (4.8%) children with PPR, Group 3 (n=41): 10-15 years, 3 (7.3%) children with PPR, and Group 4 (n=20): >15 years, 5 (25.0%) children with PPR. Twelve of the 13 children with a PPR had generalized epilepsy (tonic-clonic 8, myoclonic 2, atypical absence 1, electrical status epilepticus during slow wave sleep 1), and 1 was without seizures.Conclusions: The incidence of PPRs in children with ASD in our study overall was 7.3% (no epilepsy 1.3%, epilepsy 12.2%), which is within the range reported by Fisher et al. (2005) of 0.3-3% in the normal population, and 2-14% in children with epilepsy. Our study found that in the ASD population, there is an association between the PPR and epilepsy, as has been previously reported in children with epilepsy without ASD. However, when age was taken into consideration, our study found an unexpectedly high rate of 25% overall with a PPR in children with ASD >15 years of age, and an even higher rate of 29.4% (5/17) when excluding children with ASD without epilepsy in that age group. This finding has not been reported previously. Larger scale studies, as well as prospective studies are needed to confirm this trend. Further studies are also necessary to identify the significance of these findings in the pathophysiology of epilepsy in children with ASD.