What is the significance and management of a burst suppression pattern on amplitude-integrated electroencephalography (aEEG) in neonates?

Burst Suppression Pattern on aEEG in Neonates: Significance and Management

Burst suppression pattern on amplitude-integrated electroencephalography (aEEG) in neonates is a severe abnormality of cerebral electrogenesis that typically indicates significant brain dysfunction and is associated with poor neurological outcomes in most cases, though timing and etiology are critical factors in prognosis.

Definition and Characteristics

• Burst suppression is defined as more than 50% of the EEG record consisting of periods of EEG voltage <10 µV, with alternating bursts 1
• On aEEG, this pattern appears as a discontinuous trace with periods of very low voltage activity interrupted by high-amplitude bursts 1
• This pattern represents severe disruption of normal brain electrical activity and is considered a "highly malignant" EEG pattern 1

Etiologies in Neonates

• Hypoxic-ischemic encephalopathy (HIE) is the most common cause of burst suppression in neonates 2
• Other causes include:
  • Meningitis 2
  • Early infantile epileptic encephalopathy (Ohtahara syndrome) 2
  • Early myoclonic epilepsy 2
  • Inborn errors of metabolism (particularly disorders of energy metabolism, hyperammonemia, and organic/amino acidopathies) 3
  • Medication effects (particularly fentanyl, midazolam, phenobarbital) 2, 4
  • Multiple organ failure 2
  • Non-ketotic hyperglycinemia and other metabolic disorders 2, 3

Prognostic Significance

• In comatose survivors of cardiac arrest (including neonates), burst suppression is usually a transient finding during the first 24-48 hours after return of spontaneous circulation 1
• Burst suppression during therapeutic hypothermia may be compatible with neurological recovery 1
• Persistent burst suppression pattern at ≥72 hours from the initial insult is consistently associated with poor neurological outcome 1
• Specific patterns like identical bursts or burst suppression associated with status epilepticus have very high specificity for prediction of poor outcome 1
• In neonates with inborn errors of metabolism, burst suppression frequently indicates severe encephalopathy 3

Special Considerations

• Non-ketotic hyperglycinemia may present with a distinctive "high-frequency burst-suppression pattern" on aEEG 3
• In KCNT1-related developmental and epileptic encephalopathies, burst suppression may be associated with synchronous heart rate fluctuations, with heart rate decreases during suppression phases 5
• Medication-induced burst suppression (particularly from fentanyl and other sedatives) generally has a better prognosis than burst suppression from primary neurological injury 2, 4
• Rarely, infants with burst suppression pattern may have normal development, though this is extremely uncommon 6

Management Approach

1. Identify and treat underlying cause:

   • Evaluate for HIE, meningitis, metabolic disorders, and medication effects 2, 3
   • Consider comprehensive metabolic workup if etiology is unclear 3

2. Seizure management:

   • Treat clinical seizures promptly to prevent additional brain injury 1, 7
   • Consider antiseizure medications if electrographic seizures are present 1, 7
   • Options include lorazepam, phenytoin, phenobarbital, valproic acid, or midazolam infusion 1, 7

3. Continuous monitoring:

   • Consider continuous EEG monitoring rather than intermittent recordings to detect seizures and monitor evolution of the pattern 1, 7
   • Monitor for at least 24 hours, particularly after rewarming if therapeutic hypothermia is used 1

4. Prognostication:

   • Avoid early prognostication based solely on burst suppression pattern, especially in the first 24-48 hours 1
   • Consider the timing, etiology, and evolution of the pattern 1
   • Medication-induced burst suppression should be distinguished from that caused by primary neurological injury 2, 4

Pitfalls and Caveats

• Sedative medications can induce burst suppression patterns that mimic those caused by severe brain injury 2, 4
• The most prudent strategy is to assess burst suppression for prognostication when any effects of sedation medications have cleared 1
• Technical factors can affect aEEG interpretation; ensure proper electrode placement and recording conditions 1
• Self-fulfilling prophecy can occur when early EEG findings influence decisions about withdrawal of life-sustaining treatment 1
• Burst suppression in neonates should not be interpreted in isolation but in conjunction with clinical examination, neuroimaging, and other biomarkers 1