Infantile Spasms

Infantile spasms are a form of epilepsy that affect babies typically under 12 months old. They look like brief spells of tensing or jerking and often happen in a cluster or series. If you think your baby is having spasms, it’s important to talk to their pediatrician as soon as possible.


What are infantile spasms?

Infantile spasms (also called epileptic spasms) are a form of epilepsy that happen to babies typically under 12 months old. Epilepsy is a group of neurological disorders characterized by abnormal electrical discharges in your brain.

Infantile spasms look like brief tensing or jerking spells that involve your baby’s abdomen (belly), head, neck, arms and/or legs. The spasms last for one to two seconds and usually happen one after another (in a series or cluster) every five to 10 seconds. Infantile spasms most commonly occur after your baby awakes from sleep.

Babies affected by infantile spasms often already have or later have developmental delays or developmental regression.

If your baby is experiencing spasms, it’s important to see their healthcare provider as soon as possible. Early diagnosis and treatment are key.


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What’s the difference between infantile spasms and West syndrome?

West syndrome happens when your baby has a combination of symptoms, including:

  • Infantile spasms.
  • Abnormal brain wave patterns called hypsarrhythmia.
  • Developmental delays or developmental regression.

While babies who’re affected by infantile spasms often have West syndrome, they can experience infantile spasms without having or later developing developmental delays.

What’s the difference between spasms and seizures?

Infantile spasms (also called epileptic spasms) are a type of seizure.

A seizure is a burst of uncontrolled electrical activity between brain cells that causes temporary abnormalities in muscle tone or movements, behaviors, sensations and/or states of awareness. Not all seizures are alike.

Spasms are typically shorter than what most people think of when they think of seizures — namely, a tonic-clonic (grand mal) seizure. Infantile spasms last around one to two seconds in a series; whereas other types of seizures can last from 30 seconds to two minutes.


What’s the difference between infantile spasms and the startle reflex?

While infantile spasms can look similar to a normal startle reflex in babies, they’re different.

The startle reflex (also called the Moro reflex) happens when a loud sound or sudden movement startles your baby. They typically throw their head back and extend their arms and legs with the palms of their hands facing upward. They may also cry and often pull their arms and legs back in.

This chart can help you tell the difference between infantile spasms and the startle reflex.

Startle reflex
Loud noises, bright light or sudden movement.
Infantile spasms
Waking up from sleep is the most common trigger, but spasms can happen at any time during the day.
Frequency and timing
Startle reflex
Happens once after a trigger and lasts a few seconds.
Infantile spasms
Often happen back-to-back or in clusters. Each spasm lasts for one to two seconds, but clusters can last for several minutes.
Age of occurrence
Startle reflex
Most noticeable in newborns and slowly disappears by four to six months of age.
Infantile spasms
Often start occurring between the ages of three and 12 months and continue.

At what age do infantile spasms start?

Healthcare providers diagnose infantile spasms in babies younger than 12 months of age in 90% of cases. The average age of diagnosis is between four and seven months of age.

When children who’re older than 12 months have spells resembling infantile spasms, they’re typically classified as epileptic spasms.


How common is this condition?

Infantile spasms affect approximately 1 in 2,000 to 4,000 babies.

Symptoms and Causes

What are the signs and symptoms of infantile spasms?

During an infantile spasm, your baby’s body will stiffen or tense up suddenly and only for a couple of seconds. They may also arch their back, and their arms, legs and/or head may bend forward. Infantile spasms often happen one after another in a cluster with five- to 10-second pauses in between spasms.

After a spasm or series of spasms, your baby may appear upset or cry — but not always.

In some cases, infantile spasms are very subtle and difficult to notice. Subtle signs of an infantile spasm include:

  • Eyes rolling up.
  • Belly tensing up.
  • Chin movements.
  • Grimacing.
  • Head nodding.

Spasms that are due to an abnormality in your baby’s brain often affect one side of their body more than the other or may result in pulling of their head or eyes to one side.

Infantile spasms are most common just after your baby wakes up and rarely happen while they’re sleeping.

Soon after your baby starts experiencing spasms, you’ll likely notice other changes in your baby, including:

  • Loss of developmental milestones they had previously reached, such as rolling over, sitting, crawling and babbling.
  • Loss of social interactions and smiling less.
  • Increased fussiness or silence.

If you can, try to take videos of your child’s spasms so you can show them to their pediatrician. It’s very important that infantile spasms are diagnosed early. If you think your baby may be having infantile spasms, talk to their pediatrician as soon as possible.

How often do infantile spasms occur?

A baby can have as many as 100 spasms a day. Each baby is affected differently, so if you notice your baby having spasms — even if it’s once or twice a day — it’s important to talk to their pediatrician as soon as possible.

What causes infantile spasms?

There are several causes of infantile spasms. Scientists have listed over 200 different health conditions as possible causes of infantile spasms. But in about one-third of cases, healthcare providers can’t determine the cause.

An infantile spasm may happen due to an abnormality in a small portion of your child’s brain or may be due to a more generalized brain issue.

Possible causes of infantile spasms include:

  • Brain injuries or infections: Almost any type of brain injury can cause infantile spasms. The most common causes include hypoxic-ischemic encephalopathy (when your brain doesn’t get enough oxygen or blood flow for a period of time), meningitis and perinatal stroke (a stroke that happens to your baby anytime between the middle of pregnancy and the first month of their life).
  • Issues with brain development: Several central nervous system (brain and spinal cord) malformations that occur while your baby is developing in the womb can cause infantile spasms. These can include focal cortical dysplasia, lissencephaly, holoprosencephaly and Aicardi syndrome. Abnormal blood vessels in your baby’s brain (arteriovenous malformations) can also cause infantile spasms.
  • Gene mutations: Scientists are linking more and more gene mutations (changes) to infantile spasms. Some of these include trisomy 21 (Down syndrome), tuberous sclerosis, Miller-Dieker syndrome and CDKL5 deficiency disorder.
  • Metabolic conditions: Inborn errors of metabolism (IEM) can cause infantile spasms. They’re genetic conditions that block metabolic pathways involved in the breakdown of nutrients you eat and the generation of energy. In rare cases, vitamin B6 deficiency also causes infantile spasms.

Diagnosis and Tests

How are infantile spasms diagnosed?

Your child’s healthcare provider will ask detailed questions about your child’s symptoms and medical history. They’ll also perform a physical exam.

Your child may have to see a pediatric neurologist or pediatric epileptologist. They’ll order a test called an electroencephalogram (EEG) to confirm the diagnosis of infantile spasms and other tests to find the cause.

Since there are hundreds of possible causes of infantile spasms, it can be more difficult for healthcare providers to identify the cause.

What tests will be done to diagnose infantile spasms?

Your child’s healthcare provider will order an electroencephalogram (EEG) to confirm the diagnosis of infantile spasms.

An EEG measures and records your child’s brain’s electrical signals. During an EEG, a technician places small metal disks (electrodes) on your child’s scalp. The electrodes attach to a machine that gives your baby’s healthcare provider information about your child’s brain activity. Ideally, the EEG will capture their brain’s activity while they’re having a spasm, as well as the time in between spasms. Healthcare providers look for a distinct EEG pattern called hypsarrhythmia. This pattern is very particular and makes it easy for healthcare providers to diagnose infantile spasms with certainty in most cases.

Tests your child’s healthcare provider may order to determine the cause of the infantile spasms include:

  • Magnetic resonance imaging (MRI) brain scan: An MRI brain scan is a painless test that produces very clear images of the structures and tissues in your child’s brain. MRI uses a large magnet, radio waves and a computer to produce the detailed images. It doesn’t use X-rays (radiation). An MRI can help your child’s healthcare provider determine what’s causing their spasms.
  • Genetic and metabolic tests: If your child’s MRI is normal, their healthcare provider will likely order other tests, such as genetic and metabolic tests, to try to determine the cause of the spasms. These tests typically require a sample of blood, urine (pee) or spinal fluid.

Management and Treatment

How are infantile spasms treated?

The main goals of treatment for infantile spasms are to stop or control the spasms and to treat the cause, if possible.

The main therapies to stop and/or manage spasms include:

  • Adrenocorticotropic hormone (ACTH): ACTH is a hormone your pituitary gland releases that plays a large role in how your body responds to stress. The release of ACTH triggers your adrenal glands to produce cortisol, the “stress hormone.” ACTH for the treatment of spasms is a synthetic (man-made) form of the hormone that’s given as a shot (injection). Your child will receive the first doses in the hospital so their healthcare provider can closely monitor them for any side effects. As your child will continue needing ACTH shots for about six weeks, their healthcare provider will give you instructions on how to give your child the injections at home.
  • Oral prednisolone: This medication is a synthetic form of a corticosteroid hormone made by your adrenal gland. It works well for the treatment of infantile spasms and can be used when there are problems with access to ACTH.
  • Vigabatrin (Sabril®): This is an anti-seizure medication. It’s taken by mouth as a pill or liquid.

If your child doesn't respond to either hormone treatments or vigabatrin, further treatment options include:

  • The ketogenic diet.
  • Other anti-seizure medicine.
  • Epilepsy surgery when there’s a focalized lesion that’s causing the infantile spasms.

Infantile spasms can be difficult to treat. Some children need a repeat course of treatment or a second treatment therapy. Throughout treatment, your child will need repeat EEG tests to check their brain activity to see if treatment is working.

If your baby’s healthcare provider can determine the cause of the spasms, they’ll need to treat the causes as well, if possible. This may include surgery or targeted therapy for an underlying genetic or metabolic condition.

Developmental delay and regression are common with infantile spasms. Your baby’s healthcare team will suggest therapies to help with development as much as possible.

What are the side effects of infantile spasms treatment?

Possible side effects of adrenocorticotropic hormone (ACTH) treatment for infantile spasms include:

Possible side effects of vigabatrin for treatment of infantile spasms include:

  • Irreversible narrowing of their field of vision.
  • Irritability.

Because of these side effects, your child’s healthcare provider will work with you to determine the best treatment option. They’ll also closely monitor your child to look for signs of these side effects.

Outlook / Prognosis

What is the prognosis (outlook) for infantile spasms?

The prognosis (outlook) for infantile spasms depends on several factors, including:

  • The cause of infantile spasms.
  • If the cause can be treated.
  • How soon your child was diagnosed and treated.
  • If your baby was reaching developmental milestones before the spasms started.

Up to 50% of children with infantile spasms have long-term developmental and neurological issues. Even if the spasms stop, many children develop other kinds of seizures and epilepsy.

If diagnosis and treatment are prompt and effective, the overall outlook is better. Normal development is possible for children who were reaching developmental milestones before their spasms started.

Living With

How do I take care of my child with infantile spasms?

To help your baby with infantile spasms, follow their healthcare provider’s instructions for:

  • Giving any medications as prescribed.
  • Getting developmental assessments and therapies.
  • Going to all follow-up medical visits.

Infantile spasms can lead to cognitive (intellectual), neurologic and/or sensory issues. Most children with infantile spasms will have problems with their development and may need help with daily tasks throughout their lives.

Your child’s healthcare team can answer questions and offer support. They also might be able to recommend a local or online support group.

When should I see my child’s healthcare provider about infantile spasms?

If your child has been diagnosed with infantile spasms, they’ll need to see their healthcare team regularly to make sure their treatment is working. They’ll also need EEG tests throughout their treatment to monitor their brain activity.

If you think your baby is having infantile spasms but hasn’t been diagnosed yet, it’s important to talk to their healthcare provider as soon as possible.

A note from Cleveland Clinic

Noticing that your baby isn’t behaving as they normally do or isn’t reaching development milestones can be concerning. You know your baby best. If you think they’re having spasms, which look like brief tensing or jerking spells, often in a series, talk to their healthcare provider as soon as possible. Try to take a video of their spasms if you can, so you can show their doctor. Early recognition of infantile spasms leads to better outcomes.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 03/09/2022.

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