the pediatric eeg


Pediatric EEG evolves into the adult

After the first month of life, a baby graduates from being a neonate to an infant, and thus also graduate from the neonatal montage to a standard 10-20 montage in terms of electrode placement. Just as with neonates, though, infants and children—particularly the first few years—have an evolving EEG that requires a good understanding of its normal timeline for proper interpretation. A key part of the pediatric EEG is its evolving PDR, discussed in detail below, but summarized as follows:

4-5 by 6 months
by 1 year
by 2 years
by 3 years
by 8 years
by 10 years


The first year of life on EEG is characterized a preponderance of slow, high amplitude delta activity. The recording should be continuous and symmetric, but not particularly reactive to eye opening until 2-4 months. After this point, a PDR of 4-5 Hz arises by 6 months of age during wakefulness. Early in this timeframe, there is significant amounts of delta activity, but as baby's approach one year of age theta frequencies become increasingly admixed. In drowsiness, though, the background is usually still very slow and high amplitude, with a lot of 1-2 Hz activity up to 200uV in amplitude, particularly early on in the first year of life. By 1 year of age, the expected PDR is 6 Hz.

Below are a few examples of normal waking tracings at various time points for infants; note the general trend, over time, of less delta and more theta, and a better formed anterior-posterior gradient. These tracings have their sensitivities lowered from the standing 7uV/mm to between 10-20uV/mm for clarity as, generally, pediatric tracings are higher amplitude than adults.

Regarding sleep, by 2 months of age stage II sleep spindles develop; initially they can be very prolonged (up to 15 seconds at a time), and can remain asynchronous till up to 2 years of age. With spindles, vertex waves in stage I, and K complexes in stage II arise, and can be extremely prominent in children; vertex waves, in particular, can be very sharp appearing and come in long runs, so don’t confuse them for B(I)RDs or seizures.

In the first months of life, up to half a baby's sleep time can be REM sleep, but this proportion decreases to about a third by 1-2 years of age. The example below is from a 4 month old healthy baby; note the high amplitude vertex wave, rather prolonged spindle in the first half of the page, and the asynchronous and poorly formed spindle near the end of the page.

You won't often try activation techniques in babies, but prolonged crying can cause a hyperventilation response, and if you do attempt photic stimulation, a slow driving response of 1-3 Hz is seen starting around 6 months of age.

early years

After the first year of life, the PDR continues to evolve, reaching 8 Hz by 3 years of age, and remains higher voltage than you'll see in adults. Most of the delta activity seen in infants' background evolves to theta in this timeframe, and alpha frequencies gradually come into the mix too. You'll also start to see some of benign variants and rhythms found in adult tracings, including lambda waves with visual scanning, and the mu rhythm as the idling activity of the sensorimotor cortex. Sleep remains very high amplitude, especially slow wave sleep.

In the set of examples below, focus on the overall progression of the gestalt background, as it moves from mostly theta at 3 years to much more alpha and beta (similar to adult tracings) by 8 years of age. Again, note that these tracings have a lowered sensitivity (10uV/mm) to allow for better clarity.

From 3-6 years of age, a new waveform also arises, posterior slow waves of youth. These are rather high amplitude, spike-like waveforms that exist within the PDR and similarly attenuate with eye opening; they are often but not requisitely bilateral in appearance, and can predominate on one side or the other. Along the same vein, there can arise slow alpha variants, which are essentially two waves from the PDR combining into one, which is thus about half the frequency of the usual PDR. Below are examples from a 5 year old patient, with a PDR of 9 Hz (normal for age). Note how the posterior slow wave of youth has a delta frequency is surrounded by the PDR without really interruping the PDR's pattern, and how the slow alpha variant has a notched appearance that should not be mistaken for an epileptiform discharge.

Note that drowsiness in children may not be accompanied by the classic slow, roving eye movements seen in adults. Throughout this time period, sleep architecture should be synchronous and essentially in line with what you see in adults, although generally more prominent and high amplitude, with vertex waves often coming in runs. You can also see hypnagogic or hypnapompic hypersynchrony, in which high amplitude, synchronized slow waves arise in the transitions from waking to sleep and sleep to waking, respectively.

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Mild generalized slowing

First of all, we know this patient is awake because we see eye blinks and a lot of frontal myogenic artifact. Second of all, this tracing has a lot of delta and theta activity, which might be normal for a very drowsy 7 year old, but in an awake patient of this age we expect to see much more alpha activity with a PDR of at least 8-9 Hz. Here, though, the PDR doesn't get past 6 Hz, and that with the excess delta and theta activity merits a call of mild generalized slowing. There is also a right temporal spike, although this patient has multifocal spikes seen elsewhere in the tracing too.

adolescence to adulthood

By the time kids reach adolescence, their EEG looks quite similar to adults, with a PDR that usually approaches 10 Hz and with a dominant mixture of alpha and beta throughout. However, unlike in adults, adolescents can have some admixed theta in their waking background, but this should fade away into the teen years.

In adolescence, the prominent hypnagogic and hypnapompic hypersynchrony of the early years recedes, and as teens grow into adults they lose posterior slow waves of youth. Sleep architecture remains quite prominent in teenagers and young adults, with vertexes continuing to often come in runs even into some patient's thirties; the example below is from a 15 year old patient.

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Abnormal: left hemispheric slowing & left temporal spikes

Recall that by 6 months of age a baby should have a PDR of 4-5 Hz. Here, we see on the right side a PDR of about 3 Hz, which is age appropriate. However, on the left side there is broad hemisphere polymorphic delta slowing, suggestive of an underlying structural abnormality. On top of that, we see a few left temporal spikes, phase reversing at T5 suggesting focal cortical hyper excitability from that area. The high amplitude, messy activity toward the end of the page is mostly movement artifact.

pediatric syndromic eeg patterns

From infancy into adulthood, there are a number of classic EEG patterns and syndromes that you should be familiar with, because each has different treatment requirements and prognosis. Here we'll give a brief overview on the more common ones that have a particular EEG signature.

Ohtahara syndrome (EIEE)

Ohtahara syndrome, now termed early infantile epileptic encephalopathy (EIEE) is a devastating diagnosis of early infancy. On EEG, its characterized by a burst suppression pattern, with high amplitude, multifocal spikes embedded within the bursts of activity. Multiple seizure types, most often tonic seizures or spasms, are seen along with significant intellectual disability and developmental delay. EIEE often leads to early death, but if not can progress into West Syndrome or Lennox Gastaut Syndrome.

hypsarrhythmia & infantile spasms

Hypsarrhythmia describes a characteristic EEG background that is very high amplitude, disorganized, slow and with multifocal epileptiform discharges throughout. As you'd expect, its a highly concerning pattern seen most often in infants in the setting of infantile spasms, or West Syndrome. This syndrome describes a triad of clinical findings including hypsarrhythmia on EEG, epileptic spasms, and developmental delay/regression. Urgent treatment is critical for this in order to prevent long term developmental sequelae and intractable seizures.

lennox gastaut syndrome (LGS)

Lennox Gastaut Syndrome (LGS) can evolve from EIEE or West Syndrome, or arise on its own. Similar to the other two, it is a severe form of epileptic encephalopathy with multiple seizure types and intellectual impairment. The classic LGS tracing is marked by diffuse, prominent slowing and slow (2.5-3 Hz) generalized spike wave discharges.

benign epilepsy with centrotemporal spikes

Benign (rolandic) epilepsy with centrotemporal spikes (BECTS) is a common, descriptive and often self-limiting disorder, marked electrographically by the aforemented centrotemporal spikes, which can be unilateral or bilateral. This condition usually emerges from 1-4 years of age, and remits by adolescence. Seizures in BECTS classically are focal nocturnal, and consist of unilateral facial spasms that can progress to involve the ipsilateral arm and leg.

absence epilepsy

While you can see absence seizures with multiple types of generalized epilepsy, the classic absence seizure, marked by 2.5 Hz generalized spike and slow waves, is seen with the syndrome of absence epilepsy. These seizures tend to be very brief and have rapid on and offset, without any postictal state; they can often be provoked by hyperventilation. The 2.5 Hz spike wave pattern is important to recognize because absence epilepsy is the only epilepsy syndrome treated first line with ethosuximide.

electricral status epilepticus of sleep (ESES)

Electrical status epilepticus of sleep (ESES)--also called continuous spike and waves during slow wave sleep (CSWS)--describes a dramatic increase in interictal activity during sleep, such spikes are present in at least 85% of non REM sleep. ESES is commonly found in Landau Kleffner Syndrome, in which children have seizures and language regression after an initially normal development, due to the presence of ESES on a nightly basis. In the example below, this patient has occasional left hemispheric predominant discharges when awake, which increase in frequency too essentially continuous as soon as she falls asleep.

juvenile myoclonic epilepsy (JME)

Juvenile myoclonic epilepsy is among the more common pediatric epilepsy syndromes, arising in adolescence with possible persistence into adulthood. Clinically it is marked by myoclonic jerks, more often in the morning, and on EEG you may see a classic, intermittent 4-6 Hz generalized spike or polyspike and slow wave pattern.

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Note that this page is captured at a very, very low sensitivity for (scalp EEG) of 70uV/mm, so on the usual reading sensitivity of 7uV/mm, all the activity here would be so high amplitude as to be unreadable. Understanding that, this tracing shows a very high amplitude, disorganized background with multifocal epileptiform discharges, consistent with hypsarrhythmia.

The pediatric EEG progresses from mostly to delta, to mostly theta, and finally to the alpha dominated adult tracing

The normal PDR progression is 4-5 by 6 mo, 6 by 1 yr, 7 by 2 yr, 8  by 3 yr, 9 by 8 yr, 10 by 10 yrs

Posterior slow waves of youth and slow/half alpha variants arise in the early years, and usually recede by late teens

Pediatric tracings tend to be higher amplitude than adults, with very prominent sleep architecture including vertex runs, and hypnagogic & hypnopompic hypersynchrony

Ohtahara syndrome is a devastating epileptic enephalopathy marked by discontinuity and high amplitude spikes

Hypsarrhythmia is defined as high amplitude, disorganized background with multifocal spikes, and is often seen with infantile spasms / west syndrome

Lennox Gastaut Syndrome has a slow background, often with 2.5-3 Hz generalized spike waves

Benign epilepsy with centrotemporal spikes is common, and usually goes away by adolescence

Absence epilepsy is marked by brief seizures of 2.5 Hz generalized spike waves, provoked by hyperventtilation

Juvenile Myoclonic Epilepsy (JME) is classically associated with faster, 4-6 Hz generalized spike wave activity

Normal for age

Here we see a tracing predominantly comprised of mix of theta, alpha and beta frequencies with a PDR of 7-8 Hz. We also know this patient is awake, due to several eye blinks across the page. Recall that the normal progression of the PDR is 4-5Hz by 6 months, 6 Hz by 1 year, 7 Hz by 2 years, 8Hz by 3 years, 9 Hz by 8 years, and 10 Hz by 10 years (though there is a little wiggle room here). So, a PDR of 7-8 for 7 year old is totally normal.

Normal development with eventual seizure resolution

This tracing shows left centrotemporal spikes that, in the context of nocturnal seizures that start with hemifacial spasms, is most consistent with benign epilepsy with centrotemporal spikes (BECTS). In most cases, this syndrome does not require treatment with anti seizure medications, although if the seizures are frequent or prolonged a focal anti seizure medication is considered. Usually this syndrome resolves on its own into the adolescent and teenage years.

This page is from a 15 year old patient; how would you grade the slowing shown? Are there any other findings of note on this page?

Severe Generalized Slowing with Multifocal Discharges

This tracing is from a patient with very severe case of Lennox Gastaut Syndrome (LGS). We see disorganization of the background with no appreciable AP gradient; the page is also high amplitude, and there are periods of discontinuity in between the high amplitude bursts of activity. Recall that discontinuity leads to a grading of severe generalized slowing. There are also multifocal epileptiform discharges throughout the page, with some marked in red below.

Normal Sleep

Here, we see what could be an early part of slow wave sleep, with high amplitude, synchronized delta activity within which there are relatively long and asynchronous sleep spindles. Recall that sleep spindles should arise by 2 months of age, become synchronous by 2 years of age, and can be quite prolonged in kids. So, this is a normal sleep tracing for a 4 month old. Given the possibility of long, asynchronous spindles in kids, don't confuse them for paroxysmal fast activity, which is an abnormal and epileptiform finding.


Here we see a background of a wide range of frequencies, including delta, theta, alpha and beta. In children, remember that delta predominates the awake background in the first year of life, and theta and alpha increase after that until you get the expected predominance of alpha and beta that you see in adult tracings. In drowsiness, however, delta is often still seen.

This tracing also shows some normal variants, including the mu rhythm (which can be quite prominent in kids) and posterior slow waves of youth, which appear as slow, posterior delta waves within which the PDR is often subtly embedded. These usually go away into and throughout the teenage years.

right temporal breach with wickets
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early years

pediatric epileptic syndromes