Infantile Spasms, West Syndrome, and IESS

By Dovy Paukstys, Founder, Komori Care

This article is educational and is not medical advice. It does not diagnose, treat, prevent, or cure any condition. Komori is not a medical device, is not FDA-cleared, does not detect seizures, and is not intended for people with epilepsy. Talk with a neurologist or epileptologist about personal medical decisions. Households living with epilepsy should use clinically validated seizure-detection devices as directed by their care team.

A lot of people still search "West syndrome" or "infantile spasms" and get three names for almost the same emergency.

I'm not a neurologist. I don't have epilepsy. I read the ILAE pages, NINDS, and the Infantile Spasms Action Network so this hub uses the current names instead of mixing them up.

The short version. IESS is the syndrome name now. West syndrome is a subset. Infantile spasms are the seizure type.

The name change is not cosmetics

ILAE's current label is infantile epileptic spasms syndrome, IESS. Onset of epileptic spasms in an infant, age 1 to 24 months.

West syndrome is inside that. The old triad: epileptic spasms, hypsarrhythmia on EEG, and developmental plateau or regression.

IESS is wider on purpose. Some infants have spasms without the full triad. ILAE still treats them as this syndrome. Same urgency.

ILAE also stamps IESS as a developmental and epileptic encephalopathy. The seizures and the cause can both hit a brain that is still wiring itself.

NINDS still uses older public language. Infantile spasms as a seizure type that usually starts before 6 months. Head drop, bend at the waist, arms jerking up, sometimes a cry. When all three features land, they call it infantile spasms syndrome, previously West syndrome. Spasms usually stop by 4 or 5. Some kids later develop other seizure types.

What a spasm looks like

Not a long convulsion. Short. Often in clusters.

NINDS: drop the head, fold at the waist, jerk the arms toward the head, cry out. Can be all of those or one of them.

The Infantile Spasms Action Network says each spasm lasts around one second, then a pause, then another. Head drops, arm raises, wide-eyed stares. Repeated every few seconds for several minutes. They also say babies can lose milestones. Babbling. Sitting. Visual tracking.

ILAE's clinical context: onset 1 to 24 months, peak 3 to 12 months. Both sexes, more boys. Some infants looked typical before this. Some already had a brain injury or an earlier syndrome such as early-infantile DEE. Development may slow or regress at spasm onset. Occasionally it doesn't. Don't wait to find out which camp you're in.

ISAN treats suspected spasms as something you act on now. Record a video. Call the pediatrician or ER and say the words "infantile spasms." Ask for an EEG. Get a neurologist. Their STOP mnemonic is See the signs, Take a video, Obtain an EEG, Prioritize treatment.

If the movements look like that, call a doctor. Tonight. Not after a long weekend of second-guessing.

EEG. Hypsarrhythmia is classic. It is not the only pattern.

ILAE mandatory seizure type: epileptic spasms.

Mandatory EEG: hypsarrhythmia, or focal or multifocal epileptiform abnormality.

Hypsarrhythmia is the messy one. High-voltage irregular slow waves mixed with multifocal spikes and polyspikes. Chaotic looking. Some infants only have focal or multifocal discharges. Still IESS if the spasms are there.

ILAE's caution: the EEG can look normal early, or only look wrong in sleep or on waking.

Ictal EEG, when they catch a spasm, often shows a high-voltage sharp or slow wave, then low-amplitude fast activity and voltage drop-off.

MRI is not required to name the syndrome. ILAE calls it highly recommended, because the cause is often structural. If the interictal EEG is not doing its job, they want an ictal recording.

A normal EEG during a suspected spasm is exclusionary. If the event is electrically quiet, it is not an epileptic spasm on ILAE's terms.

In a clinic with no EEG machine, ILAE allows diagnosis if an experienced clinician sees clusters of spasms, live or on video, and the other mandatory pieces fit. They still want EEG when they can get it.

Causes

ILAE lists four buckets. Structural brain abnormalities, developmental or acquired. Tuberous sclerosis. Hypoxic-ischemic injury. Chromosomal disorders such as Down syndrome or Miller-Dieker. Gene changes, including ARX, CDKL5, SPTAN1, STXBP1. Metabolic causes.

ISAN's family page says the same map. Brain structure problems present at birth or acquired. Genetic conditions including TSC, CDKL5, Dup15q. Down syndrome. Some cases with no found cause.

The gene names above overlap the long-tail DEEs. Those have their own pages on Rare Epilepsy Long Tail.

Why speed gets talked about so much

ISAN's line is that spasms can harm a rapidly developing brain if they sit untreated. They say prompt treatment raises the chance of better developmental outcomes, especially when there is no underlying brain disorder.

I'm not inventing a treat-within-X-hours number I did not fetch. Direction is the same on the pages I opened. Don't wait. Get an EEG. Let a neurologist pick the therapy. Hormonal therapy and vigabatrin show up as first-line options in the clinical literature. I'm not dosing them. I'm not ranking them.

What happens later

NINDS: spasms usually stop by 4 or 5. Some children develop other seizure types.

ILAE notes IESS can follow early-infantile DEE, and later some of those kids meet criteria for Lennox-Gastaut syndrome. LGS is a different syndrome. Same family of hard epilepsies. Different EEG. Different age window.

CDC first aid still applies if you're looking at a seizure. Stay. Safe. Side if they're down. 911 if it lasts over 5 minutes or repeats. Spasms are usually seconds and clustered. First aid is not the diagnosis. EEG plus a clinician is.

What this page cannot do

It cannot tell you a startle is a spasm. It cannot read a video. It cannot replace an EEG.

Households living with epilepsy should use clinically validated seizure-detection devices as directed by their care team. A phone camera used to show a neurologist a cluster is documentation. A consumer monitor is not a seizure detector and is not a treatment.

ISAN, Child Neurology Foundation, and CURE Epilepsy are the public orgs on this one. NINDS lists them.

FAQ

Are infantile spasms, West syndrome, and IESS the same thing?

Not exactly. IESS is ILAE's current syndrome name for epileptic spasms starting between 1 and 24 months. West syndrome is the older triad: spasms, hypsarrhythmia, developmental plateau or regression. Infantile spasms are the seizure type. IESS includes kids who do not meet the full West triad.

What does a spasm look like?

NINDS describes a head drop, waist bend, arms jerking up, sometimes a cry. ISAN says about one second, in clusters, every few seconds, for several minutes. Can look subtle. Can look like a startle. A neurologist and an EEG settle it.

Is hypsarrhythmia required?

No. ILAE accepts hypsarrhythmia or focal/multifocal epileptiform abnormality. Hypsarrhythmia is classic. It is not the only legal EEG.

Who do you call if you think you saw this?

A physician. Pediatrician, ER, pediatric neurologist. ISAN says record a video and ask for an EEG. I agree with the urgency. I am not the person who reads the tracing.

Sources

• ILAE / epilepsydiagnosis.org, IESS overview: https://www.epilepsydiagnosis.org/syndrome/west-syndrome-overview.html
• ILAE / epilepsydiagnosis.org, IESS diagnostic criteria: https://www.epilepsydiagnosis.org/syndrome/west-syndrome-diagcriteria.html
• ILAE / epilepsydiagnosis.org, IESS EEG: https://www.epilepsydiagnosis.org/syndrome/west-syndrome-eeg.html
• NINDS, Epilepsy and Seizures (infantile spasms / West syndrome section): https://www.ninds.nih.gov/health-information/disorders/epilepsy-and-seizures
• Infantile Spasms Action Network, Is it Infantile Spasms?: https://infantilespasms.org/for-families/is-it-infantile-spasms/
• Infantile Spasms Action Network home: https://infantilespasms.org/
• CDC, First Aid for Seizures: https://www.cdc.gov/epilepsy/first-aid-for-seizures/index.html
• ILAE / epilepsydiagnosis.org, Encephalopathy: https://www.epilepsydiagnosis.org/encephalopathy.html