A functional classification of seizures and its distribution in a mentally retarded population

A functional classification of seizure impairment was described and its distribution examined in a population classified as mentally retarded in childhood and followed to age 22. Twenty-five percent of the sample had some history of seizures up to age 22. Seizure histories were found for 19% of these retarded persons in the preschool years and 13% in each period of early, late, and postschool years. A drop in minor seizure impairment occurred after age 5. A slightly higher frequency of seizure histories among males was found, largely due to subjects whose IQs were 50 to 59, where 44% of the males and 5% of the females had seizure histories. No significant association was found between degree of seizure impairment and severity of mental retardation.