Unfortunately, the outcome is typically poor. Spasms often do not respond to treatment or relapse. Children with IS often develop additional seizure types and have developmental disabilities. A multicenter prospective observational cohort study demonstrated response rates of 55% to adrenocorticotropic hormone (ACTH), 39% to oral corticosteroids, 36% to vigabatrin, and 9% to all other treatments.1 Furthermore, 18% of responders later relapsed.1 Additional analysis demonstrated that the presence or absence of hypsarrhythmia did not affect response to treatment.2 The greatest predictor of response in either analysis was choice of treatment, not underlying etiology. However, this study does provide further support that there are preferred treatments for IS: ACTH, corticosteroids, and vigabatrin.