The differential diagnosis for neonatal seizures is voluminous. Important causes include the following:
* Seizures resulting from hypoxic-ischemic encephalopathy may be seen in both term and premature infants. They frequently present within the first 72 hours of life. Seizures may include subtle, clonic, or generalized seizures.
* Intracranial hemorrhage occurs more frequently in premature than in term infants. Distinguishing infants with pure hypoxic-ischemic encephalopathy from those with intracranial hemorrhage often is difficult.
Metabolic disturbances include hypoglycemia, hypocalcemia, and hypomagnesemia. Less frequent metabolic disorders, such as inborn errors of metabolism, are seen more commonly in infants who are older than 72 hours. Typically, they may be seen after the infant starts feeding.
Intracranial infections (which should be ruled out vigorously) that are important causes of neonatal seizures include meningitis, encephalitis (including herpes encephalitis), toxoplasmosis, and cytomegalovirus (CMV) infections. The common bacterial pathogens include Escherichia coli and Streptococcus pneumoniae.
While most cerebral malformations present with seizures at a later age, major malformation syndromes are important to consider. Lissencephaly, pachygyria, polymicrogyria, and linear sebaceous nevus syndrome can present with seizures in the neonatal period.