It's very common for newborns and infants to startle. They fling their arms and legs wide, then bring them together. In most cases, this is a normal reflex known as the startle, or Moro, reflex. However, in rare cases, these movements may be a sign of a serious condition called infantile spasms.
Afsaneh Talai, M.D., Pediatric Neurologist at Children's Health℠ and Assistant Professor at UT Southwestern, explains how to tell the difference between normal baby movements and an infantile spasm.
What are infantile spasms?
Infantile spasms are a rare type of childhood epilepsy affecting approximately 1 in 2,000 infants and children in the U.S. each year. The spasms are tiny seizures that can have a big impact on a baby’s development. Infantile spasms most often begin when a baby is 3 to 12 months old.
Infantile spasms can cause serious, permanent changes to a child's developing brain without early diagnosis and treatment. Medication or surgery often stops the spasms, but some children are at risk for other types of seizures later in life. If children are treated quickly and successfully, they are more likely to have healthy development.
What is the difference between infantile spasms and West syndrome?
Infantile spasms refere to a specific type of seizure, while West Syndrome describes a set of symptoms that include infantile spasms. A baby has West syndrome when they have infantile spasms and:
- Hypsarrhythmia, an abnormal pattern of electrical waves in the brain. This pattern is measured by a test called the electroencephalogram (EEG).
- Developmental regression (where a child loses the ability to do something they were previously doing, like walking or talking) or developmental delays (meeting milestones later than other children their age).
What causes infantile spasms?
Infantile spasms can be related to:
- Genetic disorders like Down syndrome or tuberous sclerosis
- Metabolic disorders
- Brain injuries or infections
- Abnormal blood vessels in the brain
- Differences in how the brain developed in the womb
- Rarely, because of a vitamin B6 deficiency
For approximately 30% of children diagnosed with infantile spasms, there's no identifiable cause.
What do infantile spasms look like?
It's not uncommon for parents to overlook infantile spasms because these tiny seizures can be subtle or look like a normal startle reflex or reflux. During an infantile spasm, a baby may stiffen and extend their arms, while scrunching up their knees or bending their neck forward.
"Typically, with infantile spasms, the baby's arms extend out suddenly, and the body may scrunch forward at the waist with the knees drawn up," explains Dr. Talai. "However, infantile spasms can also be mild and look like just a head bob or the baby's eyes rolling up."
Infantile spasms only last a second or two but often come in a cluster (multiple spasms in a row). Infantile spasms commonly occur around times of sleep, especially when a child is waking up. After a spasm, babies will often be irritable or cry.
Infantile spasms vs. startle reflex
Infantile spasms and a startle reflex can look similar, but some key characteristics can help you tell the difference:
- Cause: Loud noises, bright light or sudden movement can cause a startle reflex. Infantile spasms can happen any time. They often happen when a baby is waking up and rarely happen when a baby is sleeping.
- Frequency: With a startle reflex, babies typically only do a movement once. Infantile spasms typically happen back-to-back, or in clusters. Each spasm may last only a second or two, or they can have a cluster of spasms lasting several minutes.
- Age: The startle reflex is most noticeable in newborns and slowly disappears by 4 to 6 months of age at the latest. Infantile spasms often occur between the ages of 3 to 12 months of age, when the startle reflex has already started to go away.
- Decline in development: If you notice the above symptoms and a decline in development, that could be a sign of infantile spasms. For example, you may notice your baby is not doing the same things they used to be able to do (like walking or talking) or see changes in how your child interacts, such as less eye contact or smiling.
What should I do if I think my baby has infantile spasms?
Infantile spasms affect your baby's brain development. Early diagnosis and treatment are critical to stopping the seizures and reducing their impact on your baby's development. If you are concerned your baby may have infantile spasms, follow your instincts. Talk to your baby's pediatrician right away.
You can prepare for the visit and help the doctor with diagnosis by:
- Recording video of a few of the spasms
- Documenting when episodes happen, how long they last and how your baby reacted
- Tracking changes in developmental milestones, such as smiling and interacting
Your child's pediatrician may refer you to a specialist for additional testing if needed.
How are infantile spasms diagnosed?
Infantile spasms are diagnosed by a pediatric neurologist, a doctor who specializes in conditions that affect the brain and nervous system. They may use one or more of the following tests to diagnose your child and to determine the cause of your child’s symptoms:
- EEG (electroencephalogram): This test measures the brain waves or electrical activity in your child’s brain. This test is vital to make the diagnosis of infantile spasms.
- Imaging tests: such as computed tomography scans (CAT scan, CT scan) or magnetic resonance imaging (MRI) that allow doctors to examine your child’s brain structure.
- Genetic testing: To check for specific causes of your child’s infantile spasms.
Children’s Health Epilepsy Center
Designated as a Level 4 Epilepsy Center by the National Association of Epilepsy Centers, Children's Medical Center Dallas provides the highest level of treatment for the most complex cases of pediatric epilepsy, with additional advanced epilepsy treatment options available at our Level 3 Epilepsy Center in Plano. Learn more about our program and services.
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