Infantile spasms (IS) is a rare type of epilepsy the occurs in infancy and childhood and is characterized by the triad of epileptic spasms, developmental delays, and a specific brain wave pattern (called hypsarrhythmia) on electroencephalography (EEG). The onset is usually in the first year of life and is typically between 4 to 8 months.
During a spasm, the body suddenly becomes stiff, the back may arch, and the arms, legs, and head may extend and bend forward. However, the spams may be difficult to notice if symptoms are more subtle. Spasms tend to occur just after a baby wakes up and rarely occur during sleep. Most spasms last 1 to 2 seconds and often occur in clusters.
Once the spasms begin, other changes may be observed such as not meeting developmental milestones, decreased social interactions, and increased fussiness. Infantile spasms typically end by age 5; however, they may be replaced with another seizure type. There are many causes associated with IS; however, the cause in some babies may be unknown.