What is the appropriate management for a 1-month-old child, born at term, presenting with seizures, normal fontanelle, and pending cerebrospinal fluid (CSF) analysis results?

Management of Neonatal Seizures in a 1-Month-Old

For a 1-month-old presenting with new-onset seizures and normal fontanelle, immediately stabilize the airway, check point-of-care glucose, obtain IV access, correct any metabolic derangements (hypoglycemia, hypocalcemia, hypomagnesemia), initiate phenobarbital as first-line antiseizure medication, and pursue urgent neuroimaging with MRI (or head ultrasound if MRI unavailable or patient unstable). 1, 2

Immediate Stabilization and Diagnostic Priorities

Airway and Vital Signs

• Ensure patent airway, adequate breathing, and circulation with continuous monitoring of heart rate, blood pressure, temperature, and oxygen saturation 1
• Establish IV or intraosseous access immediately 1

Critical Laboratory Testing

• Point-of-care glucose must be checked immediately to exclude hypoglycemia, which is a treatable metabolic cause of neonatal seizures 1, 3
• Measure electrolytes including sodium, calcium, and magnesium urgently 1
• Correct hypocalcemia and hypomagnesemia BEFORE initiating anticonvulsants, as these metabolic derangements can cause seizures and must be addressed first 1
• If hypoglycemia is present, treat with D10%-containing isotonic IV solution at maintenance rate 1

Cerebrospinal Fluid Analysis Considerations

• Do NOT perform lumbar puncture in a comatose infant without experienced physician evaluation due to herniation risk 1
• When CSF is obtained safely, interpret results cautiously: CSF with >20 WBC/mm³ or >10 PMN/mm³ should NOT be attributed to seizures alone and suggests infection 4
• Normal CSF values at 95th percentile for seizure patients: 8 WBC/mm³, 4 PMN/mm³, protein 73 mg/dL, glucose 119 mg/dL 4

Understanding the Etiology

Age-Specific Causes in Neonates (0-29 days, but applicable to 1-month-old)

The underlying cause can be identified in approximately 95% of neonatal seizures 5, 6:

• Hypoxic-ischemic encephalopathy (HIE) is the dominant cause, accounting for 46-65% of cases 5, 1, 6

  • 90% of HIE-related seizures occur within the first 2 days of life 5, 1, 6
  • At 1 month of age, HIE becomes less likely unless there was a recent hypoxic event

• Intracranial hemorrhage and perinatal ischemic stroke account for 10-12% of cases 5, 6

• Infection, genetic disorders, and malformations of cortical development become MORE likely when seizures occur beyond day 7 of life 5, 6

  • Given this patient is 1 month old, infection (meningitis/encephalitis) must be strongly considered
  • Treat suspected infection with empirical antibiotics immediately 1

• Metabolic derangements including hypoglycemia, hyponatremia, hypocalcemia, and hypomagnesemia are critical treatable causes 1, 3

Neuroimaging Strategy

First-Line Imaging

• Head ultrasound is the initial bedside imaging modality if the infant is unstable or MRI is unavailable 5, 1
  • US identifies intraventricular hemorrhage, hydrocephalus, and white matter changes 5
  • US alone identifies an etiology in approximately 38% of neonatal seizure cases 5
  • Limitations: Low sensitivity for hypoxic-ischemic injury and limited visualization of small infarctions, congenital anomalies, and encephalitis 5

Gold Standard Imaging

• MRI with diffusion-weighted imaging is the gold standard for identifying the etiology of neonatal seizures 5, 1, 3
  • MRI shows findings in 11.9% of patients not apparent on cranial ultrasound 5
  • MRI contributes additional diagnostic information in 39.8% of patients beyond ultrasound 5
  • Diffusion-weighted imaging is most sensitive for detecting hypoxic-ischemic injury when performed at the appropriate time interval 5
  • MRI has the greatest sensitivity for detecting malformations of cortical development 5
  • Absence of major cerebral lesions on MRI is highly predictive of normal neurological outcome 5

Role of CT

• CT is helpful in identifying structural anomalies but has lower sensitivity than MRI 5
• CT may be useful only if the patient is too unstable for MRI and urgent surgical intervention is suspected 5

Antiseizure Medication Management

First-Line Treatment

• Phenobarbital is the first-line antiseizure medication for neonatal seizures regardless of etiology 2
• Exception: If channelopathy is suspected (e.g., family history), use phenytoin or carbamazepine instead 2

Second-Line Options

• If seizures do not respond to phenobarbital, use phenytoin, levetiracetam, midazolam, or lidocaine as second-line 2
• In neonates with cardiac disorders, levetiracetam may be the preferred second-line agent 2

Medication Discontinuation

• Following cessation of acute provoked seizures without evidence of neonatal-onset epilepsy, discontinue antiseizure medications before discharge home, regardless of MRI or EEG findings 2
• This early discontinuation is recommended to avoid unnecessary long-term medication exposure 2

Additional Considerations

Pyridoxine Trial

• Consider a trial of pyridoxine in neonates with seizures unresponsive to second-line medications, particularly if clinical features suggest vitamin B6-dependent epilepsy 2

Seizure Burden and Outcome

• Treating neonatal seizures (including electrographic-only seizures) to achieve lower seizure burden may be associated with improved outcomes 2
• Continuous EEG monitoring is recommended given high rates of subclinical seizures in neonates with HIE 7

Critical Pitfall

• Do not assume normal fontanelle excludes serious intracranial pathology—neuroimaging is still essential to identify treatable causes and predict prognosis 5, 1