West syndrome is characterized by a specific type of seizure (infantile spasms) seen in infancy and childhood. This syndrome leads to developmental regression and causes a specific pattern, known as hypsarrhythmia (chaotic brain waves), on electroencephalography (EEG) testing. The infantile spasms usually begin in the first year of life, typically between 4-8 months. The seizures primarily consist of a sudden bending forward of the body with stiffening of the arms and legs; some children arch their backs as they extend their arms and legs. Spasms tend to occur upon awakening or after feeding, and often occur in clusters of up to 100 spasms at a time. Infants may have dozens of clusters and several hundred spasms per day. Many disorders leading to brain injury, such as birth problems, cerebral anomalies, metabolic disorders, and genetic disorders can lead to these spasms, making it important to identify the underlying cause. In some children, no cause can be found. Some children have spasms as the result of brain lesions, and surgical removal of these lesions may result in improvement.