Screening electroencephalograms in autism spectrum disorders: evidence-based guideline.

The purpose of this study was to establish guidelines for the use of screening electroencephalograms (EEGs) in autism spectrum disorders to identify subclinical epileptiform activity. MEDLINE and EMBASE were searched for relevant articles. The evidence was reviewed using the methodology of the Canadian Task Force on Preventive Health Care. A priori criteria were established for article selection and for grading the quality and strength of the evidence. Seizures are common, occurring in 20 to 30% of patients based on the majority of studies. Epileptiform EEG abnormalities are present in 10.3% to 72.4% of patients and subclinical abnormalities in 6.1% to 31%. Evidence for the effectiveness of anticonvulsants and corticosteroids in reducing seizures and/or autistic symptoms is based primarily on case series and case reports, with only one published randomized trial. There is currently insufficient evidence to recommend for or against the use of screening EEGs in autistic patients. Given the frequency of seizure disorders in this patient population, a high index of clinical suspicion should be maintained for subtle symptoms of seizures.