What Is West Syndrome?

West syndrome is a type of epilepsy that affects babies. It’s named after the doctor who discovered it. You might hear it called infantile spasms.

Who Gets West Syndrome?

This condition is rare. It affects fewer than 6 babies out 10,000. Most infants get it before they’re a year old, usually between months 4 and 8. A little over half of babies who have West syndrome are boys.

What Happens in West Syndrome?

It causes seizures. They only last a few seconds, but they happen in bunches called clusters. There can be as many as 150 seizures in a cluster, and some babies can have up to 60 clusters a day.

Usually, the spasms stop by the time a child is 4 years old. But most people who had it will have other kinds of epilepsy or seizure conditions as children and adults.

Babies with West syndrome usually have mental disabilities later in life, but up to 1 in 5 will have normal mental skills or only mild mental disabilities. Some will have autism.

Types of West Syndrome

Doctors may talk about three kinds of West syndrome. They are:

  • Symptomatic: When another condition caused West syndrome and your baby’s doctor knows what it is.
  • Cryptogenic: When your baby’s doctor thinks another condition caused it but doesn’t know what it is.
  • Idiopathic: When your baby was developing normally physically and mentally before West syndrome, and the cause is something in his or her genes rather than another health condition.
WebMD Medical Reference Reviewed by Dan Brennan, MD on July 04, 2019



National Organization for Rare Disorders: “West syndrome.”

Medscape: “Infantile Spasm (West Syndrome).”

National Institutes of Health, Genetic and Rare Disease Information Center: “West syndrome.”

Epilepsy Foundation: “Infantile Spasms,” “Infantile Spasms (West’s Syndrome) and Tuberous Sclerosis Complex,” “West Syndrome (Infantile Spasms).”

Epilepsia: “The underlying etiology of infantile spasms (West syndrome): Information from the United Kingdom Infantile Spasms Study (UKISS) on contemporary causes and their classification.”

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