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West syndrome (infantile spasms)

Infantile spasms are a type of epilepsy with a characteristic age of onset (typical age when seizures start), pattern of seizures and electroencephalogram (EEG). This means that it is an ‘electroclinical epileptic syndrome’. The syndrome is called ‘West syndrome’ after Dr West, who first described the condition in his 4-month-old son in 1841. This type of epilepsy occurs in about one in 2,500-3,000 children. Every year in the UK about 350-400 children will develop West syndrome.


In 9 out of 10 children with the condition, infantile spasms occur in the first year of life, typically between 3 and 8 months old. To begin with, the attacks are usually brief and infrequent and do not occur in clusters. Therefore it is quite common for the diagnosis to be made late. The parents may initially be told their infant has colic because of the pattern of the attacks and the cry that a child gives during or after an attack.

The typical pattern is of a sudden flexion (bending forward) in a tonic (stiffening) fashion of the body, arms and legs. Sometimes, the episodes are different, with the arms and legs being flung outwards (these are called ‘extensor’ spasms). Usually, they affect both sides of the body equally.

Typically, each episode lasts just 1 or 2 seconds, there is then a pause for a few seconds followed by a further spasm. While single spasms may happen, infantile spasms usually happen in ‘runs’ or ‘clusters’ of several in a row. It is common for babies who have infantile spasms to become irritable and for their development to slow up or even to go backwards until the spasms are controlled. These babies can also behave as if they cannot see. These problems can improve if the spasms can be controlled and the EEG improves.


The diagnosis of infantile spasms is made by a combination of the typical features with a typical EEG. The EEG shows a very disorganised pattern called ‘hypsarrhythmia’. The EEG is always abnormal in children with West syndrome but sometimes this abnormality is seen only during sleep. Infantile spasms, like many other ‘electroclinical syndromes’, have lots of different causes. A particular cause will be found in 7 or 8 out of every 10 children with West syndrome. A video of the spasms is also very helpful.

Most children with infantile spasms will need a number of tests apart from the EEG. These include brain scans, blood tests, urine tests and, sometimes, spinal fluid and other tests in order to try to identify the underlying cause. The most important brain scan is the magnetic resonance imaging (MRI) scan.


The main treatments used are corticosteroids or vigabatrin (Sabril). Nitrazepam and sodium valproate (Epilim) may also be used. There are different types of steroid that can be used. These are prednisolone (given by mouth), hydrocortisone (given by mouth or sometimes by injection) or tetracosactide (given by an intramuscular injection). Steroids must be used carefully as this treatment may cause some unpleasant side-effects. Vigabatrin may also be associated with some side-effects. Ketogenic dietary therapy (often called the ketogenic diet) may also be helpful for some infants.

There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.

If your child has this syndrome they may have prolonged or repeated seizures. Your child’s doctor will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.

Information about treatments for children can be found on the Medicines for Children website.


In some children, infantile spasms respond easily to treatment, whereas in others they keep on happening. Most children unfortunately go on to have other kinds of seizures in later childhood including an epilepsy syndrome called Lennox-Gastaut syndrome. Most children also have learning difficulties and these may be mild or severe. The long-term outlook for West syndrome, for both the spasms stopping and the child’s development and learning, depends mainly on the cause of the syndrome.


Charity for families of disabled children.
Freephone helpline: 0808 808 3555
Website: contact.org.uk
Email: helpline@contact.org.uk

The UK Infantile Spasms Trust
Provides a network of support to families of children affected by infantile spasms (West syndrome).
Website: ukinfantilespasmstrust.org

What is a syndrome?

A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.

If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact Epilepsy Action.


Epilepsy Action would like to thank Drs Richard Appleton and Rachel Kneen (at Alder Hey Children’s Hospital, Liverpool) and Stewart Macleod (at Yorkhill Children’s Hospital, Glasgow), consultants who specialise in children’s epilepsy, who have updated this fact sheet.


This information is exempt under the terms of Epilepsy Action's information quality standards.

  • Updated June 2016
    To be reviewed June 2019

Comments: read the 5 comments or add yours


I am a disability advocate researching on a family of a 5 month old daughter, we know nothing about this West syndrome, the parents have already been told as well as her seizures she will have Quadraplegic Cerebral Palsy, the baby in being transferred to a unit in London but it won't until October when a bed will become available the young parents are devastated.

Submitted by Ann Ling on

My son always felt limber/floppy and didn't seem to want to do much. I also thought he was colicky as an infant. At about 9 months old I heard a loud cry and noticed he was experiencing a cluster of spasms lasting 16 minutes within intervals of 9 to 12 seconds. I took him to the emergency room. We soon started seeing a neurologist who was very curious to learn why. He had EEG study done, lumbar puncture and blood tests done. My little guy was diagnosed with WS/IS and was placed on ACTHAR intramuscular injections which I had to apply very early every morning as a 30 days treatment. We immediately noticed that the spasms stopped on the 2nd day of his treatment. Thank God, he is now 16 months and spasms free till this day. He's developmentally delayed and we're getting him all the treatment he needs. We work with him every day by applying his PT & OT to his every day living. ST is also very important, which helped with him being able to finally eat some textured foods. I only pray to God that he gives our family the patience to learn more about how to help him with his disability. And for our son to continue to work hard in getting stronger in trying to catch up to his milestones.

Submitted by Sabrina on

My granddaughter who is 15 months started having spasms 2 weeks ago. The doctor said she had IS.
Since she has been having 4-5 spasms a day.
From what I have to read. It says we should take her to A&E immediately.
But a doctor friend said its best to wait for an appointment with a consultant.

I am confused? What should we do?

Please help!2

Submitted by Andrea Jolen on

Dear Andrea

Thank you for your post.

It can be a stressful and worrying time waiting to see the consultant.

It is not easy for us to say when someone should go to the hospital. It will depend on the individual’s situation.

It may be best to talk to the doctor who diagnosed your granddaughter with IS. They should give you advice on what to do if she has another seizure while she is waiting for her appointment with the consultant.

Generally, a person with epilepsy would not go to A&E unless their seizure needed medical intervention to stop it. For most people their seizures will stop on their own.  Here is a link to our first aid information.

For example, with infantile spasms typically, each episode lasts just 1 or 2 seconds, there is then a pause for a few seconds followed by a further spasm. While single spasms may happen, infantile spasms usually happen in ‘runs’ or ‘clusters’ of several in a row.

A&E will only deal with the immediate seizures. The will not diagnose or suggest any treatment for your granddaughter. They will say she has to wait to see the consultant.



Epilepsy Action Helpline Team

Submitted by rich on

My son is 7 weeks old and has jackknife like jerks only when sleeping, for a few weeks now, which occur in clusters and awakens him usually. He crunches forward when this happens then back, moving his head rapidly and sucking his hands vigorously or sticking his tongue out.
I am getting him checked out but is this likely to be benign or something serious the process of getting him checked here is long so I am frantically worrying until the appointment comes through.
Many thanks

Submitted by Dee (a very wor... on

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