NICU

Neonatal Seizure

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Neonatal Seizure, Newborn Seizure, Seizure Disorder in Newborns

  • See Also
  1. Seizure
  2. Infantile Spasms
  3. Pediatric Spell
  • Epidemiology
  1. Incidence: 1.8 to 3.5 per 1000 live births
  2. Highest Incidence in preterm and Low Birth Weight Infants
  • Types (Order of decreasing frequency)
  1. Background
    1. Generalized tonic-clonic Seizures do not typically occur in the immature nervous system of a neonate
    2. Neonatal Seizures typically start focally and then generalize
  2. Subtle findings
    1. Transient horizontal Eye Deviation
    2. Transient Bradycardia
    3. Apneic episodes
    4. Drooling
    5. Sucking
    6. Lip smacking
    7. Chewing
    8. Tongue thrusting
    9. Swimming or pedaling motion
  3. Generalized Tonic Seizure (Preterm Infants)
    1. Prolonged limb extension
  4. Multifocal Clonic Seizure (Full-Term infants)
  5. Focal Clonic Seizure (Full-Term more then Preterm)
    1. Focal rhythmic jerking
  6. Myoclonic (Both Preterm and Full-Term)
  7. Infantile Spasms (2-3% of childhood Epilepsy)
    1. Associated with serious underlying conditions (e.g. Tuberous sclerosis, Phenylketonuria, Agenesis of the Corpus Callosum)
  • Causes
  1. Background
    1. Neonatal Seizure causes are often identified (idiopathic cases are less common)
  2. Asphyxia or Hypoxic Encephalopathy (12-24 hours after birth)
    1. Consider Induced Therapeutic Hypothermia after Seizure aborted
    2. Results from perinatal asphyxia (Incidence 3-4 per 1000 full term infants)
    3. Responsible for 50% of chronic Neonatal Seizures (often starting within the first day of life)
  3. Interventricular Hemorrhage
    1. Often have no external signs of Head Trauma
    2. May present with Vomiting, irritability, poor feeding, breathing irregularity
  4. Hydrocephalus
  5. Microcephaly
  6. Electrolyte imbalance
    1. Hypomagnesemia
    2. Hypoglycemia (Serum Glucose <60 mg/dl)
      1. Seizure occurs in 50% of symptomatic Neonatal Hypoglycemia cases
    3. Hypocalcemia
      1. Early onset occurs after loss of placental Calcium transfer, and Parathyroid immaturity, and resolves spontaneously
      2. Late onset (after 96 hours) requires additional management
      3. Seizures resolve with Calcium Gluconate 100-200 mg/kg over 5-10 minutes
    4. Hyponatremia (Serum Sodium <125 mg/dl)
      1. Causes include SIADH, renal Impairment, Congenital Adrenal Hyperplasia
      2. Avoid rapid correction
    5. Hypernatremia (Serum Sodium >145 mg/dl)
      1. Causes include inadequate fluid intake, GI losses, Diabetes Insipidus, Cystic Fibrosis
      2. See Hyponatremia Management
      3. Treat active Seizures with 3% Hypertonic Saline at 3-5 ml/lg (may repeat if Seizure persists)
  7. Infection (esp. if mother had peripartum infectious symptoms)
    1. TORCH Infection (esp. Toxoplasmosis, CMV, HSV)
    2. Coxsachievirus
    3. Escherichia coli
    4. Group B Streptococcus (GBS Sepsis)
    5. Meningoencephalitis
      1. Perform full Sepsis workup including Lumbar Puncture, cultures, and start empiric Antibiotics
  8. Inborn Errors of Metabolism (including Amino Acid disturbance)
    1. Obtain Serum Ammonia
    2. Obtain serum or Urine Ketones
  9. Injury
    1. Non-accidental Trauma
  10. Drug Withdrawal (esp. age <2 years)
  11. Pyridoxine Deficiency (Vitamin B6)
  12. Vitamin K Deficiency
  13. Cardiac Disorder (e.g. channelopathy)
    1. Obtain Electrocardiogram
  14. Dysgenic brain
  15. Neonatal sleep Myoclonus
  16. Benign familial Neonatal Seizures
  17. Benign idiopathic Neonatal Seizures (Fifth Day Fits) or familial
    1. Onset in first 3-5 days of life
    2. Resolves in weeks
  • Labs
  1. Bedside Fingerstick Glucose (most important single lab test in Neonatal Seizure)
  2. Serum Sodium
  3. Serum Calcium
  4. Serum Magnesium
  • Imaging
  1. Head Imaging
    1. Evaluate for Intracranial Hemorrhage or Cerebrovascular Accident
  • Evaluation
  1. Requires broad evaluation (e.g. Neonatal Sepsis, Birth Trauma, inborn error of metabolism)
  • Management
  1. See Status Epilepticus
  2. Seizure abortive measures
    1. See Seizure Emergency Management
    2. Step 1: Diazepam 0.3 mg/kg rectally or Midazolam 0.05 to 0.15 mg/kg
    3. Step 2: Phenobarbital 20 mg/kg slow IV push
      1. May repeat dose at 10 mg/kg slow IV push
      2. Risk of apnea, respiratory depression and Hypotension
      3. Phenobarbital much higher efficacy in newborns than Levetiracetam
      4. Sharpe (2020) Pediatrics 145(6) +PMID:32385134 [PubMed]
    4. Step 3: Choose One
      1. Phenytoin or Fosphenytoin 18 mg/kg IV over 20 min (10 min for Fosphenytoin)
      2. Levetiracetam 40 mg/kg IV
        1. May repeat for a second dose at 20 mg/kg
        2. Preferred agent if there is a comorbid cardiac disorder
  3. Reversible cause management
    1. Hypoglycemia Management
      1. See Neonatal Hypoglycemia
      2. Give D10W 2-5 ml/kg IV (D5W 10 ml/kg)
      3. Evaluate for underlying cause of Neonatal Hypoglycemia
    2. Pyridoxine Dependent Encephalopathy
      1. Pyridoxine 100 mg IV
      2. Observe for apnea
    3. Neonatal Sepsis
      1. Empiric Neonatal Sepsis treatment should include Acyclovir
      2. Evaluation with cultures and Lumbar Puncture
    4. Other measures
      1. Severe Hyponatremia Management (6 ml/kg 3% saline)
      2. Severe Hypocalcemia management (50-100 mg/kg Calcium Gluconate over 10-20 min)
      3. Severe Hypomagnesemia management (2-4 ml 2% MgSO4)
      4. Consider Folate replacement
  • References
  1. (2016) CALS Manual, 14th ed, p. I-210
  2. Claudius (2023) Pediatric Pearls: Neonatal Seizures, EM:Rap, December, accessed 12/1/2023
  3. Diggs, Mok and Collyer (2026) Crit Dec Emerg Med 40(5): 27-37