Etiologies of Neonatal Seizures
Points to Remember
- Leading cause of neonatal seizures in full-term infants.
- This diagnosis should never be one of exclusion.
- Data supporting this diagnosis (history of prolonged labor, perinatal depression, prolonged resuscitation) should be obtained and documented.
- Second most common cause of neonatal seizures in full-term infants.
- Most common presentation is right-sided clonic seizures due to infarction in the left middle cerebral artery territory.
- Cerebral vein thromboses can lead to venous infarcts.
- In term infants, subarachnoid hemorrhage is more associated with subsequent seizure than subdural hemorrhage.
- Infratentorial subdural hemorrhages require urgent evaluation due to risk of brainstem compression.
- In preterm infants, intraventricular hemorrhage is the most common type of ICH (see below).
Infections of the CNS
- Can occur in utero (CMV, toxoplasmosis) or perinatally (herpes simplex, bacterial meningitis with GBS or Escherichia coli being most common).
- Prognosis can be very grim.
- Transient causes (hypoglycemia, hypocalcemia, hyponatremia); see Chapter 34 for further information.
- Inborn errors of metabolism (pyridoxine dependency, nonketotic hyperglycinemia, urea cycle defects, glutaric aciduria (type II), maple syrup urine disease, organic acidurias, cofactor deficiencies, mitochondrial defects , Zellweger Syndrome).
- Defects of neuronal migration (heterotopias).
- Defects of neuronal organization (polymicrogyria).
- Cerebral malformation (holoprosencephaly).
- Usually will display associated dysmorphic features on physical examination.
Day of Life
Hypoxic ischemic encephalopathy
Maternal drug use
All of the above
Inborn errors of metabolism
Oral–buccal–lingual or ocular movements
Autonomic dysfunction (Δ in HR, BP, Spo2)
Rhythmic, slow jerking
Facial, extremity, or axial involvement
Focal or generalized
Sustained limb posturing
Asymmetric position of trunk/neck
Focal or generalized
Rapid isolated jerks
Generalized, multifocal, or focal
Spontaneous or provoked by stimulus
Flexion/extension are equivalent
Diminished by repositioning
Abolished with containment
Benign neonatal sleep myoclonus
Bilateral or unilateral
Synchronous or asynchronous
Occurs during sleep
Not due to a stimulus
Focal or generalized
Severe CNS dysfunction
EEG may show cortical spike-wave discharge
Hyperekplexia (stiff-man syndrome)
Autosomal dominant and recessive forms
Excessive startle responses to unexpected stimuli
Excessive stiffness following startle response
Benzodiazepines reduce symptoms
- Support respiratory and cardiovascular function (may require endotracheal intubation and mechanical ventilation).
- Place on continuous cardiorespiratory monitoring.
- Correct any known causes of seizures (see above).
- If seizures continue after correction of transient metabolic derangements, load with phenobarbital (20 mg/kg IV); can be followed by repeat doses of 5–10 mg/kg IV to a total dose of 40 mg/kg IV, if needed.
- If seizures continue, load ...
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