West Syndrome

Reviewed by Neha Pathak, MD on August 18, 2020

What Is West Syndrome?

West syndrome is a type of epilepsy that affects babies. It’s named after the doctor who discovered it. Experts have many names for it, including:

  • Infantile spasms (IS)
  • Epileptic spasms
  • X-linked infantile spasm syndrome
  • X-linked infantile spasms
  • Tonic spasms with clustering
  • Hypsarrhythmia
  • Lightning spasms
  • Generalized flexion epilepsy
  • Infantile epileptic encephalopathy
  • Infantile myoclonic encephalopathy
  • Massive myoclonia
  • Salaam or jerk knife spasms

Symptoms of West Syndrome

West syndrome causes seizures. They last only 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. Sometimes, they don’t happen in clusters at first.

Children with West syndrome may have other symptoms such as:

  • Crankiness
  • Loss of appetite
  • Changes in sleep patterns, such as sleeping more during the day and less at night
  • Acting like they can’t see
  • Slowed development
  • Regression

West Syndrome Causes and Risk Factors

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.

Things that can cause West syndrome include:

  • Changes in your child’s genes
  • Metabolic disorders
  • Unusual brain development or formation
  • Brain injury from a lack of oxygen
  • Other brain injuries
  • Brain infection

Types of West Syndrome

Your doctor may talk about three kinds of West syndrome, depending on the cause:

  • Symptomatic. Another condition caused West syndrome, and your baby’s doctor knows what it is.
  • Cryptogenic. The doctor thinks another condition caused it but doesn’t know for sure.
  • Idiopathic. Your baby was developing the way they should before West syndrome, and the cause isn’t known.

West Syndrome Diagnosis

If your child’s doctor suspects West syndrome, they’ll ask for detailed information about your child’s seizures. Try to take a video before the appointment so you can show them what the seizures look like. This can help your doctor figure out if it’s West syndrome, which is often mistaken for colic.


If your child is having seizures, they’ll need an electroencephalogram (EEG) to record the patterns of electrical activity in their brain. These patterns can show the difference between West syndrome and other seizure disorders.

Your child may have these tests:

  • Your doctor will do an EEG with your child awake.
  • If the first EEG doesn’t show the expected brain pattern, they may do another one while your child is sleeping.
  • An MRI or CT scan could show where in your child’s brain the seizures are happening. They also can rule out other conditions.
  • Urine, blood, or cerebrospinal fluid (CSF) tests can help to find the cause. These may include gene tests.

West Syndrome Treatment

Treatments can help control the seizures. These may include:

If your child has developmental delays, other types of therapies and assistance may help. These may include occupational therapy and postural aids.

West Syndrome Outlook

Usually, the spasms stop by the time a child is 4 years old. But most people who had West syndrome will have other kinds of epilepsy or seizure conditions when they’re older.

Babies with West syndrome usually have mental disabilities or trouble learning later in life, but up to 1 in 5 will have typical mental skills or only mild mental disabilities. Some will have autism. Early diagnosis and treatment can help limit the long-term effects.

WebMD Medical Reference



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.”

Medical Home Portal: “Infantile Spasms.”

Institute for Child Development: “West Syndrome.”

Epilepsy Action: “West syndrome (infantile spasms).”

Cedars Sinai: “West Syndrome.”

© 2020 WebMD, LLC. All rights reserved.