What an EEG Shows After Newborn Seizures and Why Silent Seizures Matter

When a baby is born after a difficult delivery, experiences oxygen deprivation, or shows signs of brain injury in the NICU, doctors often order a test called an EEG, or electroencephalogram, to see what the eyes cannot detect. An EEG measures electrical activity in the brain and is the most reliable way to diagnose many neonatal seizures accurately. Understanding what this test shows and why it matters can help you make sense of your baby’s diagnosis, treatment plan, and long-term outlook.

An EEG measures electrical activity in the brain and is the only way to diagnose many neonatal seizures accurately. Understanding what this test shows and why it matters can help you make sense of your baby’s diagnosis, treatment plan, and long-term outlook.

Why Your Doctor Orders an EEG for Your Newborn

When a baby is born with complications such as oxygen deprivation, infection, or stroke, doctors watch closely for signs of brain injury. Seizures are one of the most common signs that the brain has been affected. However, relying only on observation can be dangerously misleading.

Research consistently shows that 80 to 90 percent of electrographic seizures in newborns have no outward signs — no jerking, stiffening, or visible movement. A baby may appear calm, breathe normally, and even sleep peacefully while experiencing significant seizure activity in the brain. This phenomenon is known as an electrographic seizure, meaning the electrical storm is visible only on an EEG monitor, not through physical observation.

Without an EEG, doctors would miss most of these seizures entirely. This is why video-EEG confirmation is considered the gold standard for diagnosing neonatal seizures, per guidance from the American Clinical Neurophysiology Society. The test allows the medical team to detect silent seizures, confirm suspected seizures, and monitor how the baby responds to treatment.

Some key reasons an EEG is ordered include:

• The baby experienced a known risk factor such as HIE (Hypoxic Ischemic Encephalopathy), birth trauma, or infection

• The baby had one visible seizure and doctors need to know if more are happening

• The baby is receiving therapeutic hypothermia or other treatments that require seizure monitoring

• The baby shows subtle behaviors that might be seizures, such as lip smacking, eye deviation, or cycling movements

The EEG is not just a diagnostic tool. It is also a window into your baby’s brain health and future risk.

What an EEG Can Detect in Your Newborn’s Brain

An EEG records the electrical signals produced by brain cells. These signals appear as wavy lines on a monitor, and trained neurologists read these patterns to identify normal brain activity, abnormal background activity, and seizure events.

During a seizure, the brain’s electrical activity changes in a specific way. Seizures on EEG have a crescendo and decrescendo pattern, meaning they build up, reach a peak, and then taper off. This beginning, middle, and end structure helps doctors distinguish true seizures from other types of abnormal brain activity.

To be classified as a seizure on EEG, the abnormal electrical pattern must last at least ten seconds. Shorter bursts of unusual activity may be flagged for review but do not meet the clinical definition of an electrographic seizure.

There are two main types of seizures in newborns:

Electrographic seizures are detected only on the EEG. The baby shows no visible movement or change in behavior. These are the silent seizures that make up the majority of neonatal seizure cases.

Clinical seizures are visible to the eye and also show up on the EEG. These may include jerking, stiffening, staring, or unusual movements. However, not all visible movements are seizures, and not all seizures cause visible movements. This is why video-EEG is so valuable: it allows doctors to match what they see on the screen with what they observe in the baby, ensuring accurate diagnosis.

The EEG also shows background brain activity, which can reveal important information about the severity of brain injury. Abnormal background patterns, asymmetry between the two sides of the brain, or absent responses to stimulation can all indicate serious underlying problems.

How EEG Results Help Predict Your Baby’s Future

One of the most important roles of the EEG is helping doctors assess the risk of long-term complications. While no test can predict the future with certainty, EEG findings are strongly linked to outcomes such as developmental delays, cerebral palsy, and epilepsy.

Research shows that neonatal neuroimaging combined with EEG can identify children at the highest risk for infantile-onset epilepsy after events like neonatal stroke. In one study, children who later developed epilepsy had specific EEG abnormalities during the newborn period, including asymmetry in brain wave patterns and absent or abnormal responses to sensory stimulation.

EEG seizure activity, even when there are no visible clinical signs, is equally associated with serious cerebral lesions and adverse clinical outcomes. This means that silent seizures are just as concerning as visible ones. They indicate that the brain is under stress and may have sustained injury.

Some of the EEG findings that may signal higher risk include:

• Persistent seizure activity despite medication

• Severely abnormal or suppressed background activity

• Asymmetry between the left and right sides of the brain

• Absence of normal sleep-wake cycles

• Lack of response to sensory stimulation

These findings do not guarantee a specific outcome, but they help doctors and families prepare for the possibility of ongoing care needs. Early identification allows for earlier intervention, which can improve developmental outcomes.

The Process of Neonatal EEG Monitoring

Understanding what happens during an EEG can help reduce anxiety about the test. The process is non-invasive and does not cause pain, though it may look intimidating at first.

Small electrodes are gently placed on the baby’s scalp using a special adhesive paste or gel. These electrodes are connected to wires that lead to the EEG machine. The baby does not feel any electricity. The electrodes simply listen to the brain’s natural electrical signals.

There are two main types of EEG monitoring used in newborns:

Single EEG recording typically lasts 30 to 60 minutes. This is often used as an initial screening tool or to check brain activity at a specific point in time.

Continuous EEG monitoring can last 24 to 48 hours or longer. This approach is preferred for babies at high risk of seizures because it captures more data and is more likely to detect silent seizures. The American Clinical Neurophysiology Society‘s updated 2025 guidelines recommend continuous EEG monitoring for neonates at high risk for seizures, including those with HIE, neonatal stroke, or intracranial hemorrhage.

Video-EEG combines the electrical recording with simultaneous video of the baby. This allows doctors to see whether any physical movements match up with seizure activity on the EEG. It is especially helpful for distinguishing true seizures from normal newborn behaviors such as startling, tremors, or sleep movements.

Many NICUs also use a simplified version called amplitude-integrated EEG, or aEEG, which provides a compressed bedside display of brain activity that can be interpreted by nursing and neonatal staff without a neurophysiology specialist present. aEEG is a useful screening tool and is widely used for continuous monitoring, especially during therapeutic hypothermia for HIE. However, aEEG has lower sensitivity and specificity than full conventional video-EEG and can miss seizures that a full EEG would detect. When aEEG raises concern for seizure activity, conventional video-EEG is typically used to confirm the finding. If your baby had aEEG monitoring in the NICU, the records from that monitoring are part of the medical documentation of your baby’s brain activity.

The monitoring is usually done in the neonatal intensive care unit (NICU), where the baby is already receiving close medical attention. Parents can often stay with the baby during the test, and nurses will explain what is happening at each step.

New York Resources and the Importance of Early Diagnosis

If your baby is undergoing EEG monitoring in New York, you have access to some of the nation’s leading pediatric neurology programs. Hospitals such as NYU Langone Health, Columbia University Irving Medical Center, and Montefiore Einstein have specialized NICU teams trained in neonatal neurology and continuous EEG interpretation.

Early and accurate diagnosis matters for several reasons. First, it allows doctors to start anti-seizure medication promptly, which may reduce the risk of further brain injury. Second, it helps families understand what to expect and plan for follow-up care. Third, it creates a medical record that documents the seizures and the response to treatment, which can be important if there are questions about the quality of care later.

In some cases, seizures are missed because an EEG was not ordered or was not interpreted correctly. Under New York law, healthcare providers have a duty to meet the accepted standard of care, which includes ordering appropriate diagnostic tests when a baby shows signs of brain injury or is at high risk for seizures. Failure to diagnose seizures in a timely manner may, depending on the facts, be considered medical negligence in New York. If you have concerns about whether your baby received appropriate monitoring, an attorney with experience in birth injury cases can review the medical records and help you understand your options.

Frequently Asked Questions

Can a Newborn Have a Seizure Without Any Visible Movement?

Yes. Approximately 80 percent of neonatal seizures are silent, meaning they produce no outward signs such as jerking, stiffening, or staring. These electrographic seizures can only be detected using an EEG. This is why doctors rely on continuous monitoring for babies at risk of brain injury.

How Long Does a Newborn EEG Test Take?

The length of the test depends on the clinical situation. A single EEG recording may take 30 to 60 minutes, while continuous monitoring can last 24 to 48 hours or longer. Continuous monitoring is often used for babies with known risk factors or ongoing seizure concerns because it provides a more complete picture of brain activity over time.

Is an EEG Painful for a Newborn?

No. The EEG is a non-invasive test. Small electrodes are gently attached to the baby’s scalp using adhesive paste or gel. The baby does not feel any electricity. The electrodes simply record the brain’s natural electrical signals. The process may look uncomfortable because of the wires and equipment, but it does not cause pain.

What Do Abnormal EEG Results Mean for My Baby’s Future?

Specific conditions linked to abnormal neonatal EEG include epilepsy, cerebral palsy, and developmental delays. Early intervention services can begin as soon as these risks are identified, regardless of whether a diagnosis has been confirmed.

Why Is Video EEG Better Than Just a Regular EEG?

Video EEG allows doctors to match the baby’s physical movements with the electrical activity recorded on the EEG. This is important because not all movements are seizures, and not all seizures cause movements. By watching the video alongside the EEG tracing, neurologists can accurately distinguish true seizures from normal newborn behaviors such as tremors, startles, or sleep movements. This leads to more accurate diagnosis and appropriate treatment.

What New York Parents Can Do After an EEG Diagnosis

If your baby is undergoing EEG monitoring, you are likely feeling overwhelmed and uncertain about what comes next. It is natural to feel anxious, but remember that the test itself is providing critical information that can guide your baby’s care. Ask your medical team to explain the results in plain language, and do not hesitate to request a second opinion if you have concerns about the interpretation or treatment plan.

Keep copies of all medical records, including EEG reports, imaging studies, and medication logs. These documents can be important for coordinating care with specialists and for understanding your baby’s medical history as they grow. If your baby is diagnosed with seizures or brain injury, ask about New York’s Early Intervention Program, which provides evaluation and services from birth to age 3 at no cost to families, including physical therapy, occupational therapy, and developmental support.

This article is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. It is also not legal advice. If you have questions about your baby’s medical care or legal rights, speak with a qualified healthcare provider or attorney who can review your specific situation.