An epileptic syndrome characterized by the triad of infantile spasms, hypsarrhythmia, and arrest of psychomotor development at seizure onset. the majority present between 3-12 months of age, with spasms consisting of combinations of brief flexor or extensor movements of the head, trunk, and limbs. the condition is divided into two forms: cryptogenic (idiopathic) and symptomatic (secondary to a known disease process such as intrauterine infections; nervous system abnormalities; brain diseases, metabolic, inborn; prematurity; perinatal asphyxia; tuberous sclerosis; etc.). (from menkes, textbook of child neurology, 5th ed, pp744-8)