Infantile spasms (West syndrome) are muscle spasms that affect a child's head, torso, and limbs. Infantile spasms usually begin before the age of 6 months.

• Most children with infantile spasms have below-normal intelligence, and more than half have severe disabilities.
• Although an exact cause cannot always be found, infantile spasms may be caused by diseases, injuries, or infections that occurred before or during birth.

Infantile spasms are treated with adrenocorticotropic hormone (ACTH) or prednisone. They generally do not respond well to medicines used to treat epilepsy. Vigabatrin, a new medicine that is available in the United States only on an investigational basis, may be an effective treatment for infantile spasms especially when they are caused by a disease called tuberous sclerosis.