Infantile Spasms

Infantile spasms are a rare but serious type of seizure that affects babies, typically between 3 and 12 months of age. These brief seizures can have significant effects on a young child’s developing brain, making early recognition and treatment critically important.

Table of contents

• What Are Infantile Spasms?
• Signs and Symptoms
• Causes and Risk Factors
• Diagnosis
• Treatment Options
• Complications and Long-Term Outlook

West syndrome, epileptic spasms, infantile spasms syndrome

What Are Infantile Spasms?

Infantile spasms are seizures (sudden episodes of abnormal electrical activity in the brain) that look like quick jerks or sudden stiffening movements in a baby’s body. They are a rare kind of epilepsy (a disorder that causes repeated seizures) that usually begins between 3 and 12 months of age, with most cases starting between 4 and 8 months^[1][5].

This condition is also known as West syndrome when spasms occur together with a specific abnormal brain wave pattern on an EEG (electroencephalogram, a test that records brain electrical activity) called hypsarrhythmia, along with developmental delay or loss of previously learned skills^[1][2]. Not all babies with spasms have West syndrome, but the two conditions are closely related.

Infantile spasms affect fewer than 1 in 1,000 babies born in the United States each year. Although rare, this condition is considered one of the most common severe epilepsy syndromes in infants^[1][5]. It is considered an epileptic encephalopathy, meaning it is a condition where both seizures and abnormal brain activity can directly contribute to developmental and behavioral problems^[8].

Signs and Symptoms

Infantile spasms can be difficult to recognize because they may look like normal baby movements or other conditions. Each spasm is very brief, lasting only one to two seconds. However, these short seizures typically occur in clusters, with spasms repeating every 5 to 10 seconds over several minutes^[1][8]. A baby may have anywhere from just a few spasms to as many as 100 in a single day^[1].

The spasms most commonly happen when a baby is waking up or just after waking, and they rarely occur during sleep^[1][5]. During a spasm, you might notice:

• Sudden stiffening or tensing of the body
• The back arching
• Arms, legs, or head bending forward
• A grimacing facial expression
• Repeated head nodding
• Head pulling to one side
• Eyes rolling upward
• Chin twitching

Sometimes the movement looks like a “jackknife,” where the head bends forward with arms flung out and knees pulled into the body^[5][15]. In other cases, the head may bend back with arms and legs straightened. The movements can be subtle, such as only a mild head nod, quick eye movements, or a small tummy crunch^[5][8]. These spasms are often mistaken for a startle reflex, colic, reflux, or hiccupping^[3][15].

After the spasms, parents may notice other changes in their baby^[1][5]:

• Crying (though not always)
• Less social interaction or fewer smiles
• Increased fussiness or unusual quietness
• Loss of developmental milestones previously learned, such as rolling over, sitting, crawling, or babbling

Because many primary care doctors and parents are not familiar with the signs of infantile spasms, diagnosis can be delayed. This delay can have serious consequences, as early treatment is critical for the best outcomes^[3][4].

Causes and Risk Factors

Infantile spasms can happen when part of a child’s brain is not working as expected or when problems affect the whole brain. It is estimated that 2 out of 3 infants with infantile spasms have a known cause for their seizures^[4]. However, in some cases, the cause remains unknown^[1][8].

Possible causes include^[1][4]:

• Problems with how the body uses energy, known as metabolic disorders (conditions affecting the body’s chemical processes), including inborn errors of metabolism and vitamin B6 deficiency
• Abnormalities in genes, which may be inherited from parents or happen randomly, such as Down syndrome, Aicardi syndrome, tuberous sclerosis, and neurofibromatosis
• Brain malformations, such as cortical dysplasia or lissencephaly (abnormal brain structure)
• Abnormal blood vessels in the brain, such as hemangiomas or arteriovenous malformations
• Head injury or lack of blood or oxygen to the brain, such as perinatal stroke or hypoxic-ischemic encephalopathy (brain damage from oxygen deprivation)
• Brain infections, such as meningitis or infections caused by syphilis, Zika virus, or cytomegalovirus

Several factors may increase the chances of a baby developing infantile spasms. Around the time of birth, these include^[1]:

• Low birth weight
• Birth complications that cause a lack of oxygen to the brain
• Very low blood sugar (neonatal hypoglycemia)

After birth, risk factors include^[1]:

• Serious head injury from an accident or trauma
• Brain infections
• Brain tumors
• Near drowning, when the brain goes without oxygen for too long

More than 200 different medical conditions have been associated with infantile spasms. This has led researchers to believe there may be a common pathway or mechanism that these conditions share, which leads to this unique epileptic syndrome^[6].

Diagnosis

Infantile spasms are diagnosed by a pediatric neurologist, a doctor who specializes in treating brain, spine, and nervous system problems in children. Prompt diagnosis and treatment are critical because even a few days or weeks of untreated spasms can rapidly harm a child’s developing brain^[1][8].

If you notice even one or two spasms, it is important to talk to your child’s doctor right away. Parents are often encouraged to record the episodes on video, as this can be very helpful for doctors in making a diagnosis^[7][8].

To diagnose infantile spasms, the doctor will complete a physical and neurologic examination. Several tests may be needed^[2][5]:

• Electroencephalogram (EEG): This test looks at electrical activity in the brain. Babies with infantile spasms often have a unique EEG pattern called hypsarrhythmia, which shows disorganized background activity with high-voltage spikes and slow waves. The doctor may want to look at EEG patterns when the child is awake, asleep, and during actual spasms^[2][8].
• Blood tests and urine tests to look for infections, illnesses, or metabolic problems^[5]
• MRI (magnetic resonance imaging) of the brain to look for structural problems, malformations, or injuries. This test remains the highest-yield initial study in determining the cause of infantile spasms^[9]
• Genetic testing and urine metabolic screening to identify underlying genetic or metabolic conditions^[7]

Early and accurate diagnosis is challenging because infantile spasms can be mistaken for normal baby movements or other disorders that do not require urgent treatment. Many pediatricians and primary care doctors find it difficult to diagnose this condition because the spasms do not look like traditional seizures^[3][4].

Treatment Options

Treatment of infantile spasms should begin as quickly as possible. Infantile spasms are considered a medical emergency, and diagnosing and treating them is an urgent matter. If not treated promptly, the disorder can permanently harm a child’s development^[8][10].

The main treatments for infantile spasms include hormonal therapy and an anti-seizure medicine called vigabatrin. While there is limited high-quality research data, these two approaches have the best evidence as first-line medications^[9]:

• High-dose prednisolone or ACTH (adrenocorticotropic hormone): Hormonal therapy is typically the first-line treatment for most children with infantile spasms, except for those with tuberous sclerosis or certain treatable metabolic conditions^[7][9]. The dosage and weaning schedule should be guided by the treating neurologist. Children taking high-dose prednisolone need close monitoring because this treatment is associated with increased risk of serious infections and adrenal crises^[7].
• Vigabatrin: This anti-seizure medicine is recommended as first-line treatment for children with tuberous sclerosis complex^[7][9]. Combination therapy with both prednisolone and vigabatrin has a higher rate of stopping spasms, but studies showed no improvement in developmental outcomes at 18 months compared to prednisolone alone^[7].

Other treatment options may include^[5][9]:

• Other anti-seizure medications if first-line treatments do not work
• Special diets, such as the ketogenic diet (a high-fat, low-carbohydrate diet that can help control seizures)
• Surgery in some cases

In rare cases, infantile spasms may be caused by vitamin B6 deficiency, and supplementation with vitamin B6 can stop the spasms^[4][15].

Treatment is always led by a neurologist who specializes in treating children with epilepsy. Hospital admission should be strongly considered when it will speed up investigations and the start of treatment^[7].

Complications and Long-Term Outlook

Even a few days or weeks of untreated infantile spasms can rapidly lead to poor growth and development of a child’s brain. This can cause more seizures later in life and lead to problems with^[1]:

• Hearing
• Speech
• Vision
• Writing
• Learning and thinking (intellectual disability)
• Small movements (fine motor skills) like using fingers or handling objects
• Large movements (gross motor skills) like walking, jumping, or climbing stairs

Children with infantile spasms are at risk for developing other types of seizures as they grow older. They also may be at increased risk for autism spectrum disorder and cognitive delays^[2][8]. Infantile spasms are associated with developmental delay in over 80% of infants and high rates of ongoing epilepsy^[7].

The long-term outcome for children with infantile spasms varies greatly and depends on several factors^[8][10]:

• The underlying cause of the infantile spasms
• Whether treatments successfully stop the spasms
• How quickly treatment begins
• Whether the child has other medical conditions

Children who had normal development before the spasms began and who do not have an identifiable underlying cause tend to have better outcomes, especially if they receive rapid diagnosis and successful treatment^[8][9]. These children have the greatest likelihood of a normal health outcome. However, many children will have poor outcomes, including continued seizures, developmental problems, and autism spectrum disorder^[8][10].

Early diagnosis and effective treatment are crucial in improving the prognosis for infants with spasms. Early responders to treatment have been shown to have better long-term epilepsy and developmental outcomes^[2].