Newborns can experience seizures, which are neurological events occurring within the first 28 days of life (the neonatal period). These occurrences are a significant medical concern because they often signal an underlying issue affecting the developing brain. Unlike seizures in older children or adults, neonatal seizures frequently present in subtle, non-convulsive ways, making them challenging to recognize immediately. Prompt identification and medical intervention are necessary, as prolonged or untreated seizure activity can potentially impact long-term neurological development.
Understanding Neonatal Seizures
A seizure is a sudden, uncontrolled electrical discharge in the brain’s gray matter, disrupting normal function. The unique characteristic of neonatal seizures stems from the immaturity of the newborn brain, which lacks the fully formed neuronal networks necessary to propagate an electrical discharge across the entire brain. This means generalized tonic-clonic seizures are rare in this age group. Instead, the electrical disturbance tends to remain localized, resulting in focal seizures or subtle, repetitive movements. The immature brain is highly susceptible to these disturbances, meaning many neonatal seizures are “provoked” by an acute medical condition rather than a chronic epilepsy syndrome.
It is important to distinguish a true seizure from benign movements, such as the startle reflex or jitteriness. Non-seizure movements can often be stopped by gently holding or repositioning the affected limb. A true epileptic movement is typically stereotypic, repeating in an identical, rhythmic pattern, and cannot be suppressed by physical restraint.
Identifying Subtle Symptoms
The most frequent form of seizure observed in newborns is the subtle seizure, which can easily be mistaken for normal newborn behavior. Caregivers must be vigilant in observing specific, repetitive movements, which can be categorized into motor, ocular, oral, and autonomic phenomena.
Motor Movements
Subtle motor movements include rhythmic actions like “bicycling” of the legs or “swimming” motions of the arms. A single limb might also exhibit tonic posturing, which is a sustained stiffening extension or flexion. These movements lack the widespread, forceful body contractions seen in older individuals.
Ocular Signs
Ocular signs frequently involve the eyes, such as sustained staring or a fixed, unblinking gaze. Rhythmic eye deviation or fluttering of the eyelids can indicate seizure activity. These movements are involuntary and occur without the baby being responsive to visual or auditory stimuli.
Oral Manifestations
Oral and facial manifestations are common due to the advanced development of the controlling brain regions. These present as repetitive sucking, chewing, or lip-smacking movements. An infant might also exhibit rhythmic tongue thrusting or protrusion.
Autonomic Changes
Autonomic changes affect involuntary bodily functions and are challenging to recognize. A concerning sign is central apnea, an unexplained cessation of breathing. Other subtle signs include changes in heart rate, fluctuations in blood pressure, or unusual skin color changes like flushing or pallor.
Common Underlying Causes
Neonatal seizures are a symptom of an underlying disruption to the central nervous system.
Hypoxic-Ischemic Encephalopathy (HIE)
The most frequent cause in full-term infants is HIE, which is brain injury resulting from a lack of sufficient oxygen and blood flow, typically occurring around the time of birth. Seizures related to HIE most commonly emerge within the first 24 hours of life.
Vascular Events
Intracranial Hemorrhage (bleeding within the brain) is a significant cause, more common in premature or low-birth-weight infants. This bleeding irritates the brain tissue, triggering abnormal electrical activity. A perinatal stroke, a blood clot restricting blood flow, can also cause seizures due to localized tissue damage.
Infections
Infections of the central nervous system, such as meningitis or encephalitis, are acute causes that provoke seizures. These infections cause inflammation and irritation of the brain and its surrounding membranes. Sepsis, a widespread bacterial infection, can also lead to seizures by causing systemic instability.
Metabolic Disturbances
Metabolic disturbances are a treatable group of causes, with low blood sugar (hypoglycemia) being a common culprit. Imbalances in electrolytes, such as low calcium (hypocalcemia) or low magnesium (hypomagnesemia), also contribute to neuronal excitability. Inborn errors of metabolism are rarer but require immediate, specific treatment.
Developmental Brain Abnormalities
Seizures can be linked to structural defects that occurred during gestation. Conditions like lissencephaly or cortical dysplasia cause the brain’s structure to be abnormal, creating areas prone to generating seizures. These structural causes often lead to seizures that are more resistant to standard medications.
Medical Diagnosis and Treatment
Once a neonatal seizure is suspected, the immediate focus is on stabilizing the baby and accurately diagnosing the event and its root cause. The definitive diagnostic tool is continuous electroencephalogram (EEG) monitoring, which records the brain’s electrical activity using electrodes placed on the scalp. This monitoring confirms that subtle clinical movements correspond to abnormal electrical discharges and detects “electrographic-only” seizures that have no visible symptoms.
A comprehensive series of laboratory tests is performed to rapidly identify correctable metabolic issues. These blood tests check for levels of glucose, calcium, magnesium, and sodium. Imaging studies, specifically magnetic resonance imaging (MRI) or computed tomography (CT) scans, are used to visualize the brain structure and detect issues like hemorrhage, stroke, or developmental malformations.
Treatment involves two parallel approaches: stopping the acute seizure and addressing the underlying cause. If a metabolic issue like hypoglycemia is found, correcting the blood sugar level often stops the seizures entirely. For the seizure activity itself, intravenous anti-epileptic drugs (AEDs) are administered to suppress the abnormal electrical firing. Phenobarbital is the preferred first-line medication for acute neonatal seizures. If seizures persist, a second drug such as phenytoin or levetiracetam may be added. The goal is short-term control, with the intention of discontinuing the medication after a period of stability, provided the underlying cause has been resolved and the EEG remains normal.