West Syndrome

Medically Reviewed by Dan Brennan, MD on February 20, 2024
6 min read

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

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

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

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.

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.

Treatments can help control the seizures. These may include:


The most common treatment for West syndrome is medication. Your doctor may want to try:

  • ACTH, a hormone
  • Vigabatrin (Sabril), a seizure medication
  • Steroids like prednisone
  • Vitamin B6, if West syndrome results from a lack of vitamin B

About two-thirds of babies who take ACTH or vigabatrin have fewer or less intense seizures. It may be a day or two before these treatments work.

Medications like ACTH, vigabatrin, and steroids can have side effects, so you and your doctor will have to balance the good and the bad for your child. The side effects of these drugs include:

Vigabatrin side effects include:

If these medications don’t work, your doctor might want to try:

Ketogenic diet

Your baby’s doctor may suggest a ketogenic diet -- one that’s high in fats and low in carbohydrates. It isn’t something you should try to do by yourself. The doctor will want you to work with a nutrition specialist. You’ll still be able to breastfeed, but you’ll also have to use a ketogenic formula. The doctor may want to admit your baby to the hospital to start the process.

The ketogenic diet can have side effects, like kidney stones, dehydration, and constipation. You and the doctor will have to watch your little one closely.


If brain scans show lesions on your baby’s brain, they might need surgery. Your doctor might suggest a corpus callosotomy, which is sometimes called split-brain surgery.

The corpus callosum is a band of nerve fibers deep inside the brain that connects the two halves. During this procedure, the surgeon will cut it so that seizure signals on one side of the brain can no longer travel to other side. Your baby may still have seizures, but they won’t be as intense.

This surgery can also treat a common cause of West syndrome, tuberous sclerosis complex. In this condition, cancerous tumors grow in your baby’s body, including the brain. Some people with this condition do better with a type of surgery called resection, in which the doctor removes parts of the brain that are causing seizures.

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

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

West syndrome can affect your child’s development and ability to think. How severe their problems are depends on what caused the condition and how they were developing before they got it:

  • If they were on track before, they may keep their mental ability or only have a mild disability.
  • If their West syndrome came from a brain disorder or an injury, they're likely to have more serious problems.

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.

About 7 in 10 babies with West syndrome have severe mental disabilities. They might get autism, especially if the syndrome came from tuberous sclerosis complex, a condition that causes noncancerous tumors in the body and brain. Or they could be hyperactive, which means it’ll be hard for them to sit still or concentrate.

It’s rare, but some children who had West syndrome as babies will die before adulthood. It usually happens before the age of 10.

Your baby is more likely to develop normally if:

  • They were at least 4 months old before they got West syndrome.
  • Their seizures aren’t unusual for West syndrome.
  • They don’t have partial seizures.
  • Their readings from an EEG -- which measures electrical activity in the brain -- are normal. (They don’t have what doctors call asymmetry.)
  • They get treated soon after their diagnosis.
  • Treatment gets their seizures under control quickly.

The future depends on what caused your baby’s West syndrome. If it's from an injury, infection, or a condition like tuberous sclerosis complex, they may not fare as well.

If there wasn’t another cause and their development was on track before it, their chances of a normal life are a little bit better than 50-50. The odds are even higher if they get treatment within a month of getting West syndrome. About 1 in 4 babies who have it will develop normally and be able to have a job when they grow up.

Parents of children with West syndrome can find -- or give -- help via the Infantile Spasms Project, an online forum run by the David Geffen School of Medicine at the University of California, Los Angeles.