Newborns often undergo various medical assessments to ensure their well-being, especially concerning their developing brain. Monitoring brain activity provides insights into neurological health, which is particularly delicate during the earliest stages of life. A specialized tool for this purpose is the neonatal electroencephalogram, commonly known as a neonatal EEG. This diagnostic procedure offers a non-invasive way to observe electrical signals within a newborn’s brain, helping professionals understand its function and development.
Understanding Neonatal EEG
An electroencephalogram (EEG) is a test that measures the electrical activity produced by the brain. It records the electrical impulses that brain cells use to communicate with each other. The term “neonatal” refers to newborns, typically babies less than four weeks old, though the EEG montage may be used until the baby reaches full-term age or around 46-48 weeks gestational age.
This procedure uses small, flat metal discs called electrodes, placed gently on the baby’s scalp. These electrodes detect electrical signals generated by the brain’s neurons, particularly from the outer layer. The detected signals are then amplified and displayed as wavy lines on a computer screen or paper, providing a visual representation of the brain’s electrical patterns. This non-invasive method allows professionals to assess the newborn’s brain function and development.
Reasons for Performing a Neonatal EEG
Medical professionals recommend a neonatal EEG when there are specific concerns about a newborn’s neurological status or development. One common indication is the suspicion of seizures, which can be subtle in newborns and difficult to identify clinically. An EEG can distinguish between epileptic and non-epileptic events, even detecting “subclinical” seizures that do not cause obvious physical movements.
The test is also performed to investigate altered states of consciousness, such as excessive drowsiness or irritability, or abnormal movements that might suggest underlying neurological issues. Other reasons include evaluating the severity of hypoxic encephalopathy, a condition resulting from reduced oxygen to the brain, or addressing concerns like hypotonia, which is unusually low muscle tone. Infants at high risk for brain injury, such as those born prematurely or who experienced complications like central nervous system infections, intracranial hemorrhage, or perinatal stroke, may also undergo an EEG. This assessment helps professionals understand the impact of these conditions on the infant’s brain and guide treatment.
The Neonatal EEG Procedure
The neonatal EEG procedure is designed to be as comfortable and safe as possible for the newborn. Before the test, the baby’s scalp needs to be clean, and sometimes a mild abrasive paste is used to ensure good contact for the electrodes. A trained technologist then places a series of small, round electrodes onto specific areas of the baby’s head.
These electrodes are held in place with a conductive glue or paste, ensuring they remain secure throughout the recording. In addition to brain electrodes, extra leads may be placed to record eye movements, chin muscle activity, and respiration. These help in determining the baby’s sleep state during the recording. The entire process, including electrode placement and recording, can take approximately 1.5 to 2 hours.
Parents are encouraged to be present during the test and can help by feeding the baby beforehand to promote sleep, as recording during different sleep states provides valuable comprehensive information. The procedure is painless and non-invasive, with no known risks to the baby. Sometimes, a flashing light or other mild stimulation may be used to observe the brain’s response.
What Neonatal EEG Results Reveal
Interpreting neonatal EEG recordings requires specialized expertise, as a newborn’s brain activity differs significantly from that of older children and adults. The results are evaluated by a neurophysiologist or neurologist who considers the baby’s conceptional age (gestational age plus chronological age) and behavioral state, such as awake, active sleep, or quiet sleep. The background activity of a neonatal EEG is assessed for continuity, symmetry, and synchrony, along with the presence of age-appropriate patterns.
Normal neonatal EEG patterns evolve with increasing conceptional age. For instance, certain patterns are normal in premature infants but disappear as the brain matures. Similarly, brain activity that appears to alternately “turn on” and “turn off” is normal in very premature babies but becomes more continuous with age.
Abnormal patterns on a neonatal EEG can indicate various neurological concerns. These may include sharp waves, spikes, or rhythmic delta activity, which can signify different types of seizures. Seizures in newborns often lack obvious clinical signs, making EEG the primary tool for their detection and confirmation. Other abnormal findings, such as persistent low voltage or severely depressed background activity, might suggest brain injury, encephalopathy, or underlying neurological conditions. The EEG findings are always considered in conjunction with the baby’s clinical presentation and other diagnostic tests to form a comprehensive picture of their neurological health.