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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.


Helpline: 0808 808 3555
Website: cafamily.org.uk
Email: info@cafamily.org.uk

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 The Information Standard.

  • Updated June 2016
    To be reviewed June 2019

Comments: read the 4 comments or add yours


Hey my nephew is 18 months now he was diagnosed with west syndrome a year ago .. He started taking sabril then the dc changed it to revotril and now he's taking 5 medicine, revotril,depakine,zonegran,kepra,topamax. We haven't seen any positive changes yet, actually he's in worse condition now. Any help might be usefull.

Submitted by Rawan on

Dear Rawan

Thank you for your post.

West syndrome can be a difficult condition to control. For this reason it’s important your nephew is being see regularly by a doctor. The ideal would be a doctor who is a specialist in epilepsy syndromes.

If epilepsy medicine isn’t working, maybe his parents could talk to the doctor about the possibility of trying the Ketogenic diet.

If we can be of any more help, please feel free to contact us again, either by email or the Epilepsy Action Helpline freephone 0808 800 5050. Our helpline is open Monday to Friday, 8.30am until 5.30pm. 



Epilepsy Action Helpline Team

Submitted by rich on

My daughter started having spasms at 6 months old. After having a cluster of spasms lasting 10 mins we called 911, with in two days she got the diagnosis of IS. We started her on KEPRA until we could get our insurance to approve ACTH. Within two weeks of her diagnosis she started her ACTH daily injections. She has been having injections for a week and has been seizure free for over 48 hrs. I hope for the best. Also I would like to say thank you to the Psychology teacher who commented, before I read that I couldn't even dare to hope my daughter could live a normal life.

Submitted by Marina on

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

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