West Syndrome


Infantile spasms (IS) are a type of seizure that is linked to an epileptic condition known as West syndrome. West syndrome affects infants and children.

Infantile spasms are linked to mental delays.


The most common symptom of infantile spasms is stiffening of the body. During the seizure the child often has:

  • Arms thrown outward away from the body
  • Knees curled toward the body
  • Upper body bending toward the knees

A less common posture during the seizure may include:

  • Legs and arms stiffened straight out from the body
  • Head thrown back

The seizure will only last one or two seconds. However, many seizures can happen, one right after the other.

Other symptoms linked to IS include:

  • Delayed mental development
  • Crying in infants during or after the seizure
  • Losing skills (regression) such as sitting, rolling over or babbling

Causes and Risk Factors

This condition is most common in infants and young children. The condition most commonly begins between 3 and 8 months old. The condition usually stops at 4 years old.

Underlying causes that have been linked to these seizures include:

  • Genetic mutations
  • Metabolism disorders
  • Unusual brain development (malformation)
  • Lack of oxygen to the brain
  • Brain injury
  • Infections that affect the brain


Infantile spasms are sometimes misdiagnosed as colic. Parents should talk with their child's doctor if they notice their child is no longer developing normally.

When the child is brought into the doctor's office, the doctor will ask about any symptoms the child is showing.

The most useful test in diagnosing seizures is an electroencephalogram (EEG). This records electrical activity in the brain. EEG can show unusual electrical activity patterns. Different types of seizures can be identified with these patterns.

Magnetic resonance imaging (MRI) and computed tomography (CT) scans may be used to study the condition. These images can also show where the seizure is happening in the brain. The scans can also rule out other possible causes such as unusual brain development.


With early treatment the seizures can be controlled. Treatment can also help the child to develop normally or more normally than they would have without treatment.

Steroids and anti-seizure medication are the most common treatments. The steroid may have adrenocorticotropic hormone (ACTH) and be injected into the muscles. Steroids might also be given in pill form.

For some children a specific diet may help their condition. The diet is called a ketogenic diet. This is a high-fat, low-carbohydrate diet used most often for children who have not responded to medications.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
Want More Information?

Cedars-Sinai has a range of comprehensive treatment options.

Looking for a Physician?

Choose a doctor and schedule an appointment.

Need Help?


Available 7 days a week, 6 am - 9 pm PT

Need Help?


Looking for a Physician

Choose a doctor and schedule an appointment.