By Dr. Dalit Cayam-Rand, MD
Neuropediatric Unit, Shaare Zedek Medical Center
Infantile spasms are a unique type of seizure disorder that appears in infancy. Although infantile spasms are rare in the general population, they are the most common type of seizure seen among babies with Down syndrome, with a prevalence of approximately three percent. They emerge between the ages of three and twelve months, peaking at four to eight months. We do not know why babies with Down syndrome are more likely to develop infantile spasms; it may be due to altered brain structure or genetic factors. We do know that when they occur, it is important to treat them promptly to ensure the best possible outcome.
While the seizures are treatable, especially if they are recognized early, the diagnosis is often delayed. This is because the seizures can be subtle, particularly when they first appear, and babies can act normally between the episodes. Infantile spasms are frequently mistakenly attributed to gastro-esophageal reflux or “regular” baby movements. In babies with Down syndrome who have hypotonia and motor delays and are more likely to have gastrointestinal issues, late identification of these seizures is common.
Infantile spasms are classified as an epileptic encephalopathy, a disease in which the epileptic activity itself may contribute to developmental impairments, beyond what is expected in Down syndrome alone. Babies who develop infantile spasms may stop progressing developmentally or lose milestones that they had previously attained. For children with Down syndrome this has important implications for both diagnosis and treatment; the developmental arrest or slowed progression may be less noticeable among Down syndrome children who already have developmental delays, leading to a later diagnosis. At the same time, for Down syndrome children it is crucial to identify and eliminate any treatable causes of developmental delay to pave the way for them to reach their full developmental potential. Encouragingly, research has shown that when infantile spasms are treated on time, babies with Down syndrome are more likely to respond to treatment than other children with infantile spasms.
Fortunately, parents can learn to recognize these seizures. What do infantile spasms look like? Infantile spasms are sudden movements of the body, involving mainly the trunk muscles. During a spasm, the trunk, back, arms and legs can suddenly arch back (extend) or bend forward (flex). Sometimes an episode can look like a sudden head bobbing or body crunching movement. Occasionally there were will also be an eye rolling movement during the event. Immediately after the spasm the baby may cry or stop moving for a short time. The seizures occur in clusters every 5-30 seconds for approximately one or two minutes. They most commonly occur right after a baby wakes up and rarely occur during sleep. If left untreated, the episodes will become more frequent and occur several times a day. Over time, these children will often lose social skills and become fussy and irritable.
In any case of movements suspicious for spasms, it is best to try to record an episode on video and show it to a pediatric neurologist. If the neurologist suspects epileptic spasms, s/he will order an electroencephalogram (EEG) to confirm the diagnosis. The EEG measures the electrical activity of the brain through placement of electrodes on the scalp, usually while the baby is sleeping. The test is not painful or invasive and has no adverse effects. When a baby has infantile spasms, the EEG shows a distinct pattern called “hypsarrhythmia” that distinguishes this type of epilepsy from others. It includes a disorganized background and frequent epileptic activity arising from several regions of the brain. If during the EEG, the baby also has spasms, there is also a specific pattern on the EEG during the events. This test will confirm the diagnosis and enable the neurologist to begin treatment as soon as possible.
Infantile spasms do not respond to regular treatments for seizures and require special medications. The two most commonly used therapies are hormonal treatment (ACTH or steroids) and vigabatrin. ACTH is given by intramuscular injection and steroids and vigabatrin are taken by mouth. There is no uniform recommended treatment protocol and every medical center has its preferred choice of medication and duration of treatment that takes into account the underlying disorder and potential adverse effects. Neurologists will often start the medication during hospitalization as in-patient treatment in order for parents or caretakers to learn to administer the medicine and to observe the baby for any side effects. In the initial period after the diagnosis, follow up visits and EEGs are done every few weeks to gauge response to treatment. The visits will be spaced out more once a sufficient response is seen.
The goals of treatment are to stop the spasms, improve the EEG background and prevent neurological deficits. If infantile spasms are left untreated, although a significant portion of babies will stop having the seizure movements, the electrical activity of the brain may remain abnormal or evolve into other abnormal patterns of activity and the neurological deficits and social regression may persist. When children do not respond to first-line treatments, there are other anti-seizure treatment options, but these are generally less effective than ACTH, steroids and vigabatrin. One such option is the ketogenic diet, a low carbohydrate, high fat diet that causes the body to produce ketones and use alternative sources of energy. This diet is highly restrictive and like medication, has potential side effects, but may be an option for certain individuals. In all babies with infantile spasms, continued developmental follow up and therapies are paramount and an integral part of the treatment plan.
Although infantile spasms can have a lasting developmental impact on Down syndrome babies, some promising studies suggest that earlier treatment leads to fewer neurological impairments. Importantly, the developmental delay that accompanies the spasms improves when the spasms stop, and timely treatment of these seizures facilitates optimal outcomes.
In summary, as a parent or caretaker of a child with Down syndrome, one of the most effective ways to ensure an optimal neurodevelopmental outcome is to look out for any abnormal involuntary movements, document them and promptly show them to a doctor. If a diagnosis of infantile spasms is made, the best thing to do is comply with the treatment protocol and continue paramedical therapies.
Points to remember:
- Babies with Down syndrome are predisposed to developing infantile spasms
- Infantile spasms appear at 3-12 months of age and are characterized by clusters of flexor or extensor movements, usually shortly after waking
- Infantile spasms can be diagnosed with a simple non-invasive test called an EEG
- Prompt recognition and treatment of infantile spasms leads to cessation of the seizures and can prevent additional neurological impairment