Clinical Pearls & Morning Reports
Published May 3, 2023
Neonatal seizures are defined as seizures occurring within 4 weeks after birth for full-term infants or within 44 weeks of postmenstrual age for preterm infants. Read the NEJM Review Article here.
Q: What are some of the common causes of neonatal seizures?
A: Most neonatal seizures are transient and result from acute metabolic disturbances, infectious processes, or acute focal cerebral lesions. Such seizures are considered to be provoked. In full-term neonates, the most common cause of provoked seizures is hypoxic ischemic encephalopathy, followed in frequency by stroke and infection. In preterm neonates, the most common cause is intraventricular hemorrhage. Neonatal epilepsy syndromes, which are uncommon, have genetic causes, and unlike provoked seizures, some of these syndromes require long-term treatment.
Q: Are seizures in neonates easy to recognize?
A: Clinical seizures in neonates can be difficult to recognize because convulsive movements in babies are often complex, irregular, or subtle. Also, several common nonepileptic motor phenomena may be difficult to differentiate from seizures in neonates. Tremor, jitteriness, and some myoclonic movements can be mistaken for seizures. They can occur without obvious cause or as symptoms of drug withdrawal, electrolyte abnormalities, hypoglycemia, or infection. They do not have EEG correlates and are not seizures.
A: The initial steps in managing neonatal seizures are to stabilize cardiovascular and respiratory function and then to identify the cause of the seizures. Treatable medical abnormalities, such as hypoglycemia and electrolyte disorders (e.g., hyponatremia), can be rapidly detected and corrected, usually leading to cessation of seizures without the need for antiseizure medication. Perinatal, birth, and family histories can provide clues to the underlying cause of seizures. Neuroimaging is considered to be essential in the detection of possible structural abnormalities in neonates with seizure. Ultrasonography of the head is a first-line test because of its ease of use and accessibility at the bedside. Genetic testing is considered if there is no clear structural explanation for the seizures, such as stroke, hemorrhage, or infection, or if they are sequential seizures, epileptic spasms, or tonic seizures. Although rare, some syndromes previously thought to be acquired as a result of perinatal insults have been found to be due to inherited or de novo pathogenic genetic variants. Therefore, clinicians are now testing more of their neonatal patients with undiagnosed seizures for genetic disorders and increasingly identifying these causes.
A: There are limited data from randomized, controlled trials to inform treatment decisions, and medications are frequently used off label. The International League against Epilepsy recommends phenobarbital as the first-line antiseizure medication, regardless of the cause (e.g., hypoxic ischemic encephalopathy, stroke, hemorrhage, or genetic causes). Potential adverse effects of antiseizure medications on the developing brain are a concern. However, the risk is generally considered to be outweighed by the consequences of uncontrolled seizures. If the neonate does not have a response to the first antiseizure medication, phenytoin, levetiracetam, midazolam, or lidocaine may be used as second-line intervention. However, there is limited evidence regarding the best medication to be used after phenobarbital has failed to control the disorder, and there are no official guidelines for selecting such a medication or determining the dose.