EEG changes and their relationship with intellectual disability in children with autism spectrum disorders in a tertiary care hospital

Abstract

Background: Autism in children is frequently associated with Intellectual disability (ID) and epilepsy. It is known that lower IQinfluences epilepsy rates; however, electroencephalographic (EEG) findings in different grades of intellectual functioning are less well studied. Objectives: This study aimed to evaluate the EEG findings and their association with the degrees of ID in children with autism. Methods: Fifty-two children, diagnosed with autism according to the DSM-IV-TR criteria, aged between 2 to 12 years, were included in the study. Participants were recruited from outpatient clinic in the Institute for Paediatric Neurodisorder and Autism (IPNA) in Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh. All of them were subjected to physical and neurological examination. Intelligence quotients (IQ) were measured in all the participants. Psychometric tests Bayley Scales of Infant and Toddler Development, Third edition (BSID III) or Weschler Intelligence Scale for Patients-Revised (WISC-R) were used for evaluating IQ. EEG recordings were done in all the participants. Results: The frequency of EEG abnormalities were observed in 51.9% participants. Among these abnormalities, 36.5% were epileptiform and 15.4% were non-epileptiform. Majority of the focal discharges, in this study were from temporal and frontal ((50% and 40% of focal discharge). Among generalized abnormalities, 89% were symmetrical spike-wave complexes. EEG abnormalities were associated with epilepsy in 66.7% of participants. ID was present in 84.6% and of them, 77% had moderate to severe ID. Mild, moderate or severe ID did not show significant association with EEG abnormalities (p>0.05). However, patients with moderate to severe ID (IQ <50) had a higher rate of EEG abnormalities compared to those without ID or mild ID (81.5% versus 18.5%) (P=0.03). Conclusion: Relatively large number of children with autism and ID had EEG abnormalities and there was a significant association with moderate to severe ID (IQ <50) and EEG abnormalities.