West Syndrome/Infantile Spasms Fast Facts

West Syndrome is a disorder characterized by seizures or spasms. The syndrome affects very young children and is commonly referred to as infantile spasms (IS).

The symptoms of IS typically begin before a baby is a year old, and the average age of onset is six months.

The spasms may be intense and involve the whole body, or they may involve only minor twitching of the extremities.

Children with IS have abnormal electrical brain activity and often have both motor and intellectual impairments.

Most children with IS will continue to have seizures beyond infancy. However, about one-third of IS cases will resolve by themselves as the child gets older.

United Brain Association

Children with IS have abnormal electrical brain activity and often have both motor and intellectual impairments.

What is West Syndrome/Infantile Spasms?

West Syndrome is a neurological disorder characterized by ongoing seizures or spasms. The seizures occur in infants, so the condition is commonly called infantile spasms (IS). Most children will continue to have seizures even after infancy, in which case the symptoms are referred to as epileptic seizures or spasms.

Symptoms of West Syndrome/Infantile Spasms

IS typically affects children between 6 and 12 months old. IS symptoms usually stop by the time the child is five years old, but other seizure-related symptoms often develop in their place.

Symptoms of IS include:

  • Spasms. The seizures of IS often involve the entire body, with a sudden bending at the waist and stiffening of the arms and legs. Spasms most often occur soon after the baby wakes or feeds. Individual spasms are typically short, lasting only a second or two. However, the spasms tend to occur in clusters that last up to 20 minutes, and a baby may have hundreds of spasms in a single day.
  • Abnormal brain wave patterns. Children with IS usually have an unusual pattern of electrical activity in their brains (hypsarrhythmia) characterized by sharp spikes in brain activity.
  • Delays in acquiring skills that require movement or coordination. Babies may also lose skills they’ve already achieved.

What Causes West Syndrome/Infantile Spasms?

IS is caused by an underlying condition or event that damages the baby’s brain. In most cases, doctors can determine the underlying cause of the syndrome, but in about a quarter of cases, no cause is apparent. Cases without an identifiable underlying cause are most likely to resolve on their own.

Conditions and disorders that may cause IS include:

  • Trauma or injury
  • Infections
  • Tuberous sclerosis complex (TSC)
  • Down syndrome
  • Sturge Weber syndrome
  • Metabolic diseases
  • Genetic defects, such as mutations of the ARX or CDKL5 genes

Is West Syndrome/Infantile Spasms Hereditary?

The heritability of IS depends on the cause of the syndrome. Some of the underlying causes of IS are genetic and can be passed from parent to child. For example, TSC is an autosomal dominant disorder, meaning that a child can inherit the condition if they receive the disease-causing gene mutation from either parent. Parents affected with TSC have a 50 percent chance of passing the disorder to their child.

IS cases caused by mutations in the ARX or CDKL5 genes are X-linked disorders. This means that the chance of inheritance varies depending on the sex of the parent and the child. These cases usually affect males, and females are generally carriers who don’t develop symptoms of the disorder. Men with the condition will pass the gene mutation to all of their daughters, who will be carriers, but their sons will be unaffected. Female carriers of the mutation will have a carrier daughter 25% of the time, a non-carrier daughter 25% of the time, an affected son 25% of the time, and an unaffected son 25% of the time.

How Is West Syndrome/Infantile Spasms Detected?

Early diagnosis and treatment of IS helps reduce the syndrome’s impact, so early detection of the disorder is crucial. IS often goes undiagnosed in its early stages because the seizures can be subtle.

Signs to watch for include:

  • Sudden bending at the waist
  • Stiffening legs
  • Curling legs in toward the stomach
  • Stiffening and holding arms to the sides or over the head
  • Head nodding or bobbing
  • Sudden eye-rolling
  • Losing balance or falling over while sitting

How Is West Syndrome/Infantile Spasms Diagnosed?

Diagnosis of IS will include exams to look for brain activity patterns characteristic of the syndrome. Further diagnostic steps will aim to determine the cause of the syndrome if the underlying condition is not already known.

The diagnostic process may include:

  • Electroencephalogram (EEG). This non-invasive exam measures the brain’s electrical activity and can detect hypsarrhythmia.
  • Imaging scans such as magnetic resonance imaging (MRI) or computerized tomography (CT). These imaging exams can detect brain abnormalities that often coincide with IS.
  • Laboratory tests (blood, urine, spinal fluid). These tests may detect infections that can cause IS.
  • Genetic testing. These tests can detect potential genetic causes of IS, including TSC and ARX, and CDKL5 mutations.


How Is West Syndrome/Infantile Spasms Treated?

Treatment of IS typically has two different components. Treatment of the underlying condition that causes IS is crucial. Direct treatment of the IS seizures is also essential because control of the seizures can help reduce developmental complications in many cases.

Commonly used seizure-control treatments include:

  • Steroid therapy (prednisone or prednisolone)
  • Adrenocorticotropic hormone (ACTH)
  • Vigabatrin
  • Other anti-seizure medications (valproate, topiramate, pyridoxine, zonisamide, clobazam, clonazepam)
  • Ketogenic diet

Surgery is sometimes recommended in cases where a very specific part of the brain is affected.

How Does West Syndrome/Infantile Spasms Progress?

Children with IS, especially those with an underlying condition that causes intellectual disability, often have intellectual impairments after infancy. Cases of IS with no discernible cause are more likely to resolve without intellectual impairment.

IS symptoms usually resolve as the child ages, but the majority of children with IS will develop other disorders such as:

  • Lennox-Gastaut syndrome
  • Focal or multifocal epilepsy
  • Autism

How Is West Syndrome/Infantile Spasms Prevented?

Most causes of IS are not preventable. However, injury prevention and prompt treatment of infections may reduce the risk of the syndrome’s development. In the absence of preventive measures, early detection and treatment of IS have the best chance of preventing future complications.

West Syndrome/Infantile Spasms Caregiver Tips

Because it affects such young children and can have subtle manifestations, IS can escape notice early on. As a parent, you must be aware of the syndrome and its potential consequences.

  • Be alert for the signs of IS. The syndrome’s spasms can be dramatic, but often they aren’t. Know what to watch for in your baby’s behavior, especially if your child has a disorder that often underlies IS. Online resources can help you understand the warning signs.
  • Know where to look for support. Living with IS is stressful for parents. Other parents who know how the disorder affects families can help you cope with the stress. In addition, local and online support groups are important sources of information and community.

Many people with seizure disorders also suffer from other brain and mental health-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with seizure disorders:

  • Many people with seizure disorders also suffer from attention-deficit/hyperactivity disorder (ADHD) or learning disabilities.
  • About a third of people with seizure disorders suffer from depression, and about a quarter suffer from anxiety.
  • People with seizure disorders are at increased risk of developing some psychotic disorders, such as schizophrenia.
  • Autism spectrum disorder is more common in people with seizure disorders.
  • Several mental disorders, including interictal dysphoric disorder, interictal behavior syndrome, and psychosis of epilepsy, are only experienced by people with seizure disorders.

West Syndrome/Infantile Spasms Brain Science

Most children with IS exhibit an unusual pattern of brain activity called hypsarrhythmia. While the chaotic brain waves of hypsarrhythmia are likely the cause of the spasms, it is less clear what causes the abnormal brain activity in the first place. As a result, researchers are pursuing several theories to explain the underlying neurological problem, including: 

  • Dysfunction in crucial nerve cells (serotonergic neurons) in the brain stem
  • Problems in communication between the brain stem and other parts of the brain
  • Immune-system problems that interfere with hormone-producing glands in the brain
  • Stress-induced release of a chemical called corticotropin-releasing hormone (CRH). CRH may cause nerve cells in the brain to be abnormally excited, thereby inducing spasms.

West Syndrome/Infantile Spasms Research

Title: Decreasing Parental Stress of Caregivers of Infants With Infantile Spasms by Using Telemedicine Technology

Stage: Recruiting

Principal investigator: Jennifer D. Coffman, BSN 

Children’s Hospital Colorado

Aurora, CO

This study plans to learn more about how the use of new telemedicine technology can help with parental stress, costs, and overall satisfaction in care. Investigators are studying this in families who have children with a specific seizure type called infantile spasms and are being treated with a medication called ACTH (adrenocorticotropic hormone). Infantile Spasms is a rare epileptic encephalopathy that occurs within the first two years of life. It is associated with complicated and expensive treatment and poor developmental outcomes. Participants will be randomly placed in one of two groups. The first group will continue with the traditional monitoring practices primarily performed by their pediatrician. The second group will use telemedicine technology to be monitored. Investigators will then compare the two groups to see any differences in parental stress, costs of care, and/or overall satisfaction with care.

The primary hypothesis is that compared to those utilizing usual monitoring, parents/caregivers of infants with IS treated with ACTH utilizing nurse-led remote biometric monitoring will report less parenting stress at 2 and 4 weeks of treatment.


Title: Genetics of Severe Early Onset Epilepsies

Stage: Recruiting

Principal Investigator: Annapurna Poduri, MD, MPH 

Boston Children’s Hospital

Boston, MA

Many children with epilepsy experience seizures that respond well to treatment. However, a few types of epilepsy are characterized by seizures that begin very early in childhood and are associated with severe intellectual and/or developmental disabilities. These conditions, known as progressive epileptic encephalopathies, are particularly severe and are often difficult to treat. These syndromes include infantile spasms, early infantile epileptic encephalopathy with suppression bursts (Ohtahara syndrome), malignant migrating partial epilepsy of infancy, early myoclonic epileptic encephalopathy, and severe myoclonic epilepsy of infancy (Dravet syndrome).

The investigators’ current research effort is focused on children with epileptic encephalopathies, in particular Ohtahara syndrome. The investigators’ goal is to identify genetic alterations (known as “mutations”) that cause Ohtahara syndrome. By doing so, the investigators hope to improve the diagnosis and treatment for this condition. It is also possible that understanding the genetic basis of Ohtahara syndrome may, in some instances, make it possible to prevent it from occurring in the future.


Title: Treatment of Refractory Infantile Spasms With Fenfluramine

Stage: Not Yet Recruiting

Principal Investigator:  Shaun Hussain, MD

University of California, Los Angeles

Los Angeles, CA

This is a phase II clinical trial in which children with refractory infantile spasms (also called epileptic spasms or West syndrome) will be treated with fenfluramine to evaluate efficacy, safety, and tolerability. Patients with infantile spasms that have not responded to treatment with vigabatrin and ACTH will be invited to participate. Study participants will undergo baseline video-EEG, receive treatment with fenfluramine for 21 days, and then undergo repeat video-EEG to determine effectiveness. Patients with favorable response will have the opportunity to continue treatment for up to 6 months.

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