Introduction: When Should Your Baby Be Checked?

Infantile spasms are a medical emergency that requires immediate attention. If you notice your baby having sudden, brief movements that look unusual—even if they happen just once or twice—you should talk to their doctor right away. These movements might look like a startle reflex, but there’s something about them that doesn’t feel quite right to most parents. Trusting your instincts as a parent is important, because you know your baby best.^[5]

Parents should seek diagnostic testing as soon as they observe any suspicious movements in their infant. The spasms typically begin between 3 and 12 months of age, with most cases starting between 4 and 8 months. Each spasm lasts only one to two seconds, but they often occur in clusters, with short pauses of five to ten seconds between each movement. The clusters can last several minutes and may happen many times throughout the day.^[1]

Early diagnosis is critical because even a few days or weeks of untreated spasms can rapidly lead to poor growth and development of a child’s brain. The longer the spasms go untreated, the greater the risk of permanent brain injury and developmental problems. This is why doctors emphasize that infantile spasms should be treated as quickly as possible, and why prompt diagnosis matters so much.^[1]

You should also seek testing if you notice changes in your baby’s development around the same time as unusual movements. These changes might include loss of skills they had already learned, such as rolling over, sitting, crawling, or babbling. Parents often notice their baby has become less social, smiles less often, or shows increased fussiness or unusual quietness. Sometimes babies stop making eye contact or lose interest in playing and interacting with others.^[5]

Diagnostic Methods for Identifying Infantile Spasms

When a doctor suspects infantile spasms, they will perform a complete physical and neurological examination of your baby. This examination checks how your baby’s nervous system is working and looks for any signs of underlying conditions that might be causing the spasms. The doctor will ask detailed questions about what you’ve observed, including when the movements started, what they look like, how often they happen, and whether your baby has had any developmental changes.^[2]

Electroencephalogram (EEG)

The most important diagnostic test for infantile spasms is an electroencephalogram, commonly called an EEG. This test looks at the electrical activity in the brain by measuring brain waves. During an EEG, small sensors called electrodes are placed on your baby’s scalp using a special paste or cap. These electrodes detect the electrical signals that brain cells use to communicate with each other. The test is painless and doesn’t hurt your baby in any way.^[2]

Babies who have infantile spasms often show a unique pattern on the EEG called hypsarrhythmia. This pattern looks chaotic and disorganized, with a mixture of large, irregular slow waves and spikes. It’s different from the normal brain wave patterns seen in healthy babies. Not every child with infantile spasms will show hypsarrhythmia on their EEG, but seeing this pattern helps confirm the diagnosis. Other abnormal EEG patterns can also be associated with infantile spasms.^[2]

Doctors often want to record your baby’s brain waves during different states to get complete information. This means the EEG may be done while your baby is awake, while they’re falling asleep, and during sleep. Sometimes doctors also try to capture the actual spasms on the EEG to see what happens in the brain during these events. This is called a video EEG or VEEG, where your baby is recorded on video at the same time the EEG is running. This combination helps doctors see the movements and the brain activity happening at the same moment.^[15]

Brain Imaging

After an EEG confirms or suggests infantile spasms, doctors usually recommend brain imaging to look for possible causes. The most common imaging test is a magnetic resonance imaging scan, or MRI. An MRI uses powerful magnets and radio waves to create detailed pictures of the inside of your baby’s brain. Unlike X-rays, MRI doesn’t use radiation, making it safer for children.^[9]

The MRI can show if there are any structural problems with how the brain developed, such as areas where the brain formed differently than expected. These are called brain malformations, and examples include cortical dysplasia or lissencephaly. The scan can also reveal if there are abnormal blood vessels, signs of old injuries, areas where the brain didn’t get enough oxygen, or effects from infections that happened before or after birth.^[1]

Sometimes doctors may also use a computed tomography scan, or CT scan, which uses X-rays to create images of the brain. However, MRI is usually preferred because it provides more detailed information about the brain’s soft tissues. In some cases, other imaging tests like a PET scan (positron emission tomography) might be used to see how different parts of the brain are functioning.^[9]

Laboratory Tests

Blood tests and urine tests are important parts of diagnosing infantile spasms because they help doctors look for underlying causes. These laboratory tests can detect infections, metabolic disorders (problems with how the body processes food and energy), or genetic conditions that might be causing the spasms.^[15]

Blood tests may check for things like blood sugar levels, electrolytes, signs of infection, and markers of genetic or metabolic diseases. Some babies with infantile spasms have conditions that affect how their body uses vitamins. For example, a deficiency of vitamin B6 can cause infantile spasms in rare cases. Testing vitamin levels helps doctors identify if this is the problem, because treating the deficiency can stop the spasms.^[15]

Urine tests, particularly a metabolic screen, look for unusual substances that shouldn’t normally be present. These substances can indicate metabolic disorders—conditions where the body can’t properly break down certain foods or substances. Catching these disorders early is important because some can be treated with special diets or medications.^[7]

Genetic Testing

Genetic testing has become increasingly important in diagnosing infantile spasms. More and more gene mutations are being linked to this condition. Genetic testing involves taking a blood sample from your baby and analyzing their DNA to look for changes or mutations in genes that are known to cause infantile spasms or related conditions.^[15]

Some genetic conditions commonly associated with infantile spasms include Down syndrome, tuberous sclerosis, Aicardi syndrome, and neurofibromatosis. Finding a genetic cause helps doctors understand why the spasms are happening and can sometimes guide treatment decisions. For example, babies with tuberous sclerosis may respond better to certain medications than others.^[1]

The results from genetic testing can take several weeks to come back because the laboratory needs time to analyze the complex genetic information. While waiting for results, doctors usually start treatment based on the clinical diagnosis and other test findings rather than delaying care.^[7]

Physical Examination Clues

During the physical examination, doctors look for specific clues on your baby’s body that might point to an underlying cause. For example, they check the skin carefully for unusual marks or spots. Babies with tuberous sclerosis often have light-colored patches on their skin called hypopigmented macules. Finding these spots can help doctors identify this condition as the cause of the spasms.^[7]

Doctors also look for signs that one side of your baby’s body is developing differently than the other. This is called early handedness, and it can suggest a problem on one side of the brain. They check if your baby’s head size is growing too quickly or too slowly compared to normal patterns. They look for unusual facial features or other physical differences that might indicate a chromosomal abnormality or genetic syndrome.^[7]

The medical history is also very important. Doctors ask about complications during pregnancy or birth, such as whether the baby was born prematurely, had a low birth weight, or experienced a lack of oxygen during delivery. They ask about any infections the mother had during pregnancy or any infections the baby has had. All of this information helps create a complete picture of possible causes.^[1]

Diagnostics Used in Clinical Trial Qualification

When researchers conduct clinical trials to test new treatments for infantile spasms, they need to be very careful about which babies they include in the study. This means they use specific diagnostic tests as standard criteria to make sure all the babies in the trial truly have infantile spasms and can be accurately compared to each other.

The primary tool used to qualify patients for clinical trials is the EEG. Researchers need to document the presence of abnormal brain wave patterns before a baby can join a study. Many trials require evidence of hypsarrhythmia or other specific EEG abnormalities that are characteristic of infantile spasms. They often require both awake and sleep EEG recordings to fully capture the brain activity patterns.^[8]

Clinical trials also require detailed video documentation of the spasms themselves. Researchers need to confirm that what parents are observing truly matches the definition of infantile spasms. The videos help ensure that all babies in the trial have the same type of seizures, making the study results more reliable and meaningful.^[8]

Brain imaging, particularly MRI, is typically required before enrolling in a clinical trial. This helps researchers understand whether the babies have structural brain abnormalities and allows them to group patients based on whether a cause has been identified. Trials may separate babies into different groups—those with a known cause (symptomatic), those with developmental delays but no known cause (cryptogenic), and those who were developing normally before the spasms started (idiopathic).^[9]

Laboratory testing is also standard for trial enrollment. Blood work must confirm that the baby doesn’t have any medical conditions that would make the experimental treatment unsafe. For example, if a trial is testing a medication that affects the liver, researchers need baseline liver function tests to make sure the baby’s liver is working normally before starting. They also check kidney function, blood cell counts, and other basic health markers.^[9]

Developmental assessments are another important component of clinical trial diagnostics. Researchers use standardized tools to measure where each baby is in terms of development—their motor skills, cognitive abilities, and social interactions. These baseline measurements allow researchers to track whether the experimental treatment helps preserve or improve development over time. Follow-up assessments are done at regular intervals during and after the trial.^[8]

Some clinical trials may require additional specialized testing depending on what they’re studying. For example, if a trial is investigating a treatment that works differently in babies with specific genetic mutations, genetic testing confirming or ruling out those mutations would be required for enrollment. Trials testing dietary therapies might need detailed nutritional assessments and metabolic testing before a baby can participate.^[9]