Infantile spasms. Infantile spasms are a seizure disorder in young infants with diverse etiologies, suggesting that they arise from any disturbance of central nervous system function during susceptible periods of development. The prognosis for normal intellectual and neurologic development parallels that of the underlying etiology. Early and appropriate treatment with ACTH may lead to seizure control in a majority of patients. The treating physician must anticipate the side effects of this modality. 