Overview of Neonatal EEG
Neonatal electroencephalography (EEG) is a test done on newborn babies to check the brain’s health and maturity. It’s like a readout of the brain’s electrical activity, sort of like a heart monitor does for the heart. Doctors often use this test to see if there are any irregularities in the baby’s normal brain activity, or to figure out how certain medical issues might be affecting the baby’s brain.
An EEG test can also help doctors identify and confirm if a baby is having seizures. It’s important to note that examining a newborn’s brain comes with some challenges. This is because the baby’s brain activity will change based on their age and whether they’re awake or asleep. So these factors have to be taken into account when reading the results of the neonatal EEG.
Complications from this procedure don’t happen very often, but in rare cases, it could lead to skin damage and infection. However, it’s an extremely valuable tool for doctors dealing with newborns with neurological conditions.
Anatomy and Physiology of Neonatal EEG
The EEG, or electroencephalogram, is a test that measures the electrical activity of the brain, specifically the signals from nerve cells in the brain called neurons. Doctors specialized in newborn care, known as neonatologists, use this test to see if a baby’s brain activity is normal or not.
How a baby’s brain activity looks on an EEG changes as they grow older, showing that their brain is developing correctly. Whenever the brain activity pattern looks different than what’s expected for a baby’s age, it may suggest there’s a problem with the brain.
EEG readings in newborns have their unique aspects as compared to older adults. It’s believed that the brain’s neurons, especially those in the outer layer called the cortex, play a significant role in generating these EEG signals. These neurons are influenced by numerous connections from a part of the brain known as the thalamus to the cortex.
Why do People Need Neonatal EEG
A neonatal electroencephalography, also known as an EEG, is a test used to study the brain function in newborns. Doctors may find it beneficial when examining various neurological conditions, such as brain disorders or seizures. It’s a way to objectively measure how well the baby’s brain is developing.
This tool is really beneficial for neonatologists, doctors who specialize in newborn care, as it helps them understand the newborn’s behavior better. Additionally, it allows pediatric neurologists, doctors who study brain diseases in children, to better understand how different brain challenges affect the baby’s brain, as well as identify and confirm if seizures are present.
Neonatal EEG might be required for several reasons, including:
- Assessing physical signs of potential seizure, such as periodic side-to-side gaze, stiff body posture, and episodes of unexplained high blood pressure or rapid heart rate.
- Confirming the presence of seizures in the newborn.
- Evaluating the severity of a condition known as hypoxic encephalopathy, which is brain damage caused by lack of oxygen.
- A situation of hypotonia, characterized by abnormally low muscle tone.
- Changes in mental status or responsiveness.
Babies at high risk for brain injury may also require a neonatal EEG. These could be infants who have or are at risk of central nervous system infection or trauma, brain bleeding, cerebral malformation, persistent high blood pressure in the lungs, hypoxic-ischemic encephalopathy (a condition caused by a lack of blood and oxygen to the brain), perinatal stroke, and congenital disorders that affect the body’s metabolism.
When a Person Should Avoid Neonatal EEG
There’s no definitive reason why a newborn baby can’t have an EEG, which is a test to measure the electrical activity in the brain. However, doctors need to be extra careful in a few circumstances:
Firstly, if a baby has anencephaly, which means they were born without large parts of the brain and skull, taking an EEG can be challenging. Secondly, if a baby has a serious scalp injury that has caused swelling, conducting EEG might be difficult. Finally, if a baby is born earlier than expected and has a very low birth weight, the EEG should be performed with extra caution to ensure their safety.
Equipment used for Neonatal EEG
The American Clinical Neurophysiology Society has changed the way they perform pediatric EEG (Electroencephalogram – a test that measures electrical activity in the brain) because the heads of newborns are smaller and there is less EEG activity in the extreme front parts of the head. As a result, the standard international system for the placement of electrodes during an EEG has been adjusted for newborns.
The usual setup for a newborn’s EEG includes placing 8 electrode sensors on specific points on the scalp. These points are known as FP1 and 2, Cz, Fz, Tz, C3, C4, T4, O2, T3, O1, P3, P4. Along with these, EKG (electrocardiogram – a test that measures heart activity) and respiration (breathing) are also monitored. To get a more detailed view, 3 additional electrodes at points Fz, Cz, and Pz might be added.
In some cases, other electrodes might be used to watch eye movements and muscle activity (EMG – electromyography). Instead of needle electrodes, sensors are placed directly on the skin, as these are safer options for newborns. To help make sense of anything unusual that comes up during an EEG, synchronized video monitoring is also suggested.
Who is needed to perform Neonatal EEG?
Several different types of medical professionals work together to perform EEGs on newborn babies. These include trained nurses, specially trained EEG technicians, doctors who specialize in treating newborns (neonatologists), doctors who treat kids (pediatricians), doctors who specialize in the nervous system (neurologists), and doctors who specialize in diagnosing and treating diseases of the nervous system (clinical neurophysiologists).
The primary roles in performing an EEG are the EEG technicians and the neonatal nurses. They are specially trained in how to safely place electrodes (small devices that record brain activity) on newborns and how to use the machine that records the brain activity (polygraphy).
Pediatric neurologists and clinical neurophysiologists help by interpreting the results of the EEG. It’s also important that the person operating the EEG is familiar with the particular challenges that can occur in newborns and can solve any problems with minimal disturbance to the other babies in the neonatal intensive care unit.
However, sometimes it can be difficult to perform the EEG because of other equipment that is vital for the baby’s care, like ventilators (machines that help the baby breathe) and machines used for specific treatments (extracorporeal membrane oxygenation, or ECMO).
In such situations, the EEG technician needs to work together with the neonatal nurses, the team of doctors, and respiratory therapists (healthcare professionals who help with breathing problems) to make sure they get a good recording without negatively impacting the baby’s care. If there’s no video monitoring available, another person might be needed to observe and note any significant activities that could affect the results of the EEG.
Preparing for Neonatal EEG
Getting ready for an EEG, a test to check the brain activity of a newborn baby, involves several steps:
1. Doctors must think about anything that could bother or upset the baby during the test.
2. They need to set up the necessary medical equipment properly.
3. Vital information about the baby, like its gestational age (how far along the pregnancy was when the baby was born) and conceptual age (the baby’s age in weeks since conception), the baby’s health condition, and other medical data, should be documented.
4. Doctors also need to be ready for anything that could interfere with the test results or create ‘artifacts’ – false readings that don’t represent the baby’s real brain activity.
5. One crucial step is to prepare the baby’s skin properly. This includes using a special conducting paste to help the EEG sensors pick up the electrical signals from the baby’s brain. The goal is to lower the ‘impedance,’ or resistance to the electrical signals, to between 5 and 10 kOhms. This helps ensure clear, accurate readings.
How is Neonatal EEG performed
Before an EEG (a test that helps doctors look at your brain activity) is done on a baby, we need to collect some important information to help us understand your baby’s condition better. We need to know how old the baby was when they were born, how many days or weeks have passed since they were born, the date of last menstrual period of the mother, any lab test results like blood gas and serum electrolyte levels, and the medicines that the baby is currently taking. We also need to ensure that your baby is healthy enough to do this test.
For this test on babies, we usually place round metal disk-like tools, which we call electrodes, on their skin using a special paste. The number of electrodes can vary depending on the preferences of the doctor. We try to place the electrodes in such a way that they do not cause discomfort for your baby. Needle-like electrodes are not used for this test on babies.
We also record your baby’s heart rate, eye movements, and breathing patterns which aid in making sense of the final EEG result. The eye movements are recorded by placing one electrode a bit above and to the side of one eye and another one a bit below and to the side of the other eye.
For the test, we use a speed of 256 hertz (cycles per second). Some common settings include a gain of 10µV/mm, a minimum time constant of 0.3 sec, and filter settings of a high pass at 0.5 Hz and a low pass at 70 Hz. The paper speeds may be set at the standard of 30 mm/sec.
At least 60 minutes are needed to capture an accurate recording of your baby’s brain activity. Although we aim to record the baby’s brain activity in both active and quiet sleep, we don’t use any sedation to make the baby sleep. The entire time, we keep a close eye on your baby’s condition and take note of it.
Possible Complications of Neonatal EEG
An EEG (which stands for electroencephalogram) is a test that’s used to look at your brain’s electrical activity. It’s usually safe, but it might cause some issues when used with newborn babies. Newborns have very delicate and sensitive skin so the complications that can occur mainly involve the skin.
For these reasons, long-term monitoring with an EEG is generally not recommended in newborns, especially those who are very premature (born earlier than expected) because skin issues can arise such as:
* Skin maceration: This means that the skin starts to break down and become very soft and moist because of the adhesive from the electrodes (little sticky patches which record the brain’s activity) and from the electrodes being pulled.
* Infection risk: Newborn babies are more at risk of getting infections because their skin is so delicate. To avoid any chance of infection, it’s important to ensure that everything is clean and that the electrodes are not placed near any cuts or stitches on the baby’s scalp.
What Else Should I Know About Neonatal EEG?
When we observe the brain activity of newborn babies, this is referred to as neonatal Electroencephalogram (EEG). The EEG results vary based on a number of factors, such as the baby’s age and whether they’re awake or asleep. In the early weeks after birth, the brain shows specific changes that signal the brain is maturing. Some doctors can even estimate a baby’s ‘brain age’ within two weeks based on these EEG results. If the brain activity doesn’t follow the normal patterns seen with maturation, this could signal a risk for abnormal brain development.
Changes in brain activity can often be tracked by the baby’s eye movements and the changes in the background activity of their brain. Generally, these changes start around 25 weeks into a baby’s gestational period and are complete by 30 weeks.
Another key part of understanding a newborn baby’s brain activity is by observing their different states of consciousness. When a baby is awake, it can be an active wakefulness (they’re moving around) or quiet wakefulness (they’re still). When they’re asleep, it can be an active sleep (their eyes move rapidly) or quiet sleep (their eyes don’t move). There can also be in-between or ‘transitional’ sleep states.
When observing the brain activity of premature babies (from 24 to 28 weeks gestation), the EEG changes often unpredictably between periods of activity and rest with bursts of high-frequency activity in certain regions of the brain. Around 28 to 31 weeks gestation, different states of activity and sleep begin to show more clearly on the EEG, and the high-frequency activity shows a decrease in amplitude as the baby ages.
From 32 to 34 weeks gestation, the sleep states become even more clearly defined with noticeable differences between active sleep and quiet sleep. By 35 to 36 weeks gestation, the baby’s sleep stages become more complex, as more connections develop in their brain. You can now clearly differentiate between periods of high- and low-brain activity during different sleep stages.
When the baby reaches 37 weeks gestation and beyond, doctors can distinguish between different sleep and wake states based on their EEG patterns. By around 44 weeks, other features replace the characteristic EEG of a full-term baby.
