The maximum age of onset is between 3 and 12 months, the peak being at 6 months. However, spasms may start from birth, or appear long after the age of 12 months, including into adulthood. Infantile spasms represent a specific type of seizure seen in an epilepsy syndrome of infancy and childhood known as West Syndrome. West Syndrome is characterized by infantile spasms, developmental regression, and hypsarrhythmia (as demonstrated by electroencephalography).