The descriptive epidemiology of infantile spasms among Atlanta children

Purpose: To determine the population-based epidemiology of infantile spasms (IS) among Atlanta children. Methods: By using data from a cross-sectional, population-based surveillance system that included 21 EEG laboratories, we identified children born in 1975-1977 in metropolitan Atlanta with IS. Cumulative incidence up to age 2 years was estimated from the number of children with IS born in the study area in 1975-1977, and age-specific prevalence was calculated from the number of children previously diagnosed with IS who lived in the study area at age 10 years. Data regarding coexisting disabilities were available from the surveillance system for developmental disabilities. Results: The cumulative incidence of IS was 2.9/10,000 live births; half of the children with IS had cryptogenic IS. The age-specific prevalence of IS was 2.0/10,000 among 10-year-old children. Eighty-three percent of 10-year-old children with a history of IS had mental retardation (MR, IQ less than or equal to 70); 56% of children with a history of IS had profound MR (IQ <20). Developmental outcome did not differ between the children with cryptogenic IS and those with symptomatic IS. Among the 10-year-old children with profound MR who were living in Atlanta at age 10 years, 12% had a history of IS. Fifty percent of children with IS developed Lennox-Gastaut syndrome (LGS) before age 11 years. Conclusions: The syndrome of IS is rare in the general population, yet a significant percentage of all children with profound MR and severe childhood epilepsy syndromes in the general population have a history of IS.