Infantile spasms (IS), also known as West syndrome, are a rare but serious type of epilepsy that mostly affects babies under one year old. Around 400 children are diagnosed with IS each year in the UK, and research shows that around 3% of children with Down syndrome will develop infantile spasms.
Because the condition is rare, it is often missed or misdiagnosed. But fast recognition and urgent treatment can make a huge difference to long-term outcomes.
What are infantile spasms
Infantile spasms are seizures caused by chaotic electrical activity in the brain. Spasms often happen in clusters, with a pause of a few seconds between each movement.
What do infantile spasms look like?
They may look like:
- Sudden head-drops
- Movements like an exaggerated startle reflex
- Arms flinging upwards or legs scrunching inwards towards the tummy
- Clusters of spasms with pauses in between
- Vacant or rolling eyes during the episode
The movements are usually brief but repeated. Sometimes, children may also slow in their development or lose skills they had already learned (developmental regression).
Why urgent diagnosis matters
Infantile spasms are a medical emergency. Untreated, IS can lead to:
Increased risk of developmental delay or regression
Ongoing epilepsy later in childhood
Permanent impact on learning and development
Research shows that every day matters – the sooner treatment starts, the better the outcome.
What to do if you suspect infantile spasms
Infantile spasms are a medical emergency. If you think that your child is having spasms, you should:
- Try to film the spasms if possible. This will allow a paediatrician or neurologist to review the movements
and identify seizures. - Take your child to the nearest paediatric A&E. Ask for your child to be reviewed urgently by an experienced paediatrician and/or neurologist. As IS is
relatively rare, it is important that your child and the video (if you have been able to get one) are assessed by someone with experience in IS. - Insist on an EEG. An EEG is a test which will allow a neurophysiologist to assess the electrical patterns in the brain. IS comes with a distinct pattern of chaotic
brain activity called hypsarrhythmia, which can be seen on an EEG. An EEG is the only way to accurately diagnose IS. Not all hospitals have the ability to do EEGs, so you may need to be referred elsewhere. However, it is important this happens quickly (within
three days).
Parent experiences
Several parents from our Positive about Down syndrome (PADS) community have shared their stories of recognising the signs and advocating for rapid treatment. Read their experiences in our Infantile spasms lived experience guide (PDF).
Further information and support
UK Infantile Spasms Trust (UKIST) – awareness videos, treatment guides, and family support
Epilepsy Action – detailed information on epilepsy syndromes
At DSUK we work with the UK Infantile Spasms Trust (UKIST) who we recommend you connect with. UKIST has an awareness video on its website that all parents of young children with Down syndrome should watch.
If you are worried about your child, trust your instincts and seek urgent medical advice.
Frequently Asked Questions
Yes, West syndrome is another name for infantile spasms.
Around 3% of babies with Down syndrome develop infantile spasms.
They can look like a head-drop or an exaggerated startle reflex. Some children may also begin to slow down in their development or lose skills, this is known as a developmental regression and is less likely if the spasms are caught early.
Because the abnormal brain activity can cause rapid developmental regression. Early treatment gives the best chance of a good outcome.
As IS is relatively rare and causes damage more quickly than some other common types of epilepsy, The standard advice for childhood epilepsy is to have a referral to a specialist within two weeks and an EEG within four weeks, and this will likely be most familiar to the doctor you are talking to. However, IS is different and requires more rapid action, so there is a chance that you may need to strongly advocate for your child to help them to get the urgent attention that they need.
The doctor who first sees your child may not have come across IS before – a GP, on average, would have to practice for 300 years before seeing a case of IS. Therefore, being able to signpost a non-specialist doctor to good research and guidelines on IS may help to get the appropriate tests and treatment quickly.
There are some things that it may be worth highlighting to the doctor reviewing your child, particularly if that doctor is not a specialist.
- Guidelines are that children with suspected IS should have an EEG within 3 days. Many forms of epilepsy do not require the same rapid diagnosis and treatment of IS. An example of clinical guidelines from Sheffield Children’s Hospital are here, and you may wish to share these. Be clear about what you are asking for: “I would like my child to be reviewed by an experienced paediatrician today and referred for an urgent EEG in line with clinical guidelines.” The doctor may refer to NICE guidelines which state that children with epilepsy should be seen within 2 weeks and have an EEG within 4 weeks. This is not appropriate for IS – please refer the doctor to the Sheffield clinical guidelines and the study by O’Callaghan et al below.
- Spasms can be less obvious in children with Down syndrome. Low tone can make the spasms less obvious, and the developmental delay associated with Down syndrome means that it can be harder to spot developmental changes or loss of skills. If you feel that your worries are being dismissed because of Down syndrome, this is called ‘diagnostic overshadowing’. You could ask “how would you deal with this if my child didn’t have Down syndrome?” or point out that “Given IS is more common in children with Down syndrome then the general population, I feel that these concerns should be taken more seriously because she has Down syndrome, as the risk is significantly higher.”
- Any delay in diagnosis and treatment can have an impact on outcomes. A large scale, international study by O’Callaghan et al found that “increasing lead time to treatment is significantly associated with decreasing developmental score at 4 years in all infants with infantile spasms”, and that this was true for any delay in treatment. If you are struggling to get an urgent referral, please ask the doctor to look up this study before making a decision. (O’Callaghan et al, The effect of lead time to treatment and of age of onset on developmental outcome at 4 years in infantile spasms: Evidence from the United Kingdom Infantile Spasms Study, Epilepsia, 52(7):1359–1364, 2011, doi: 10.1111/j.1528-1167.2011.03127.x)
- If you are still concerned that your concerns are not being addressed, it may be worth being explicit about what you feel the risk is. “Are you 100% confident that any delay in referral/diagnosis/treatment will not risk permanent damage, and if not, are you saying that you are comfortable taking that risk?”