What are the basics of electroencephalogram (EEG) in pediatrics?

EEG Basics in Pediatrics

EEG in pediatric patients requires age-specific technical adaptations, with a minimum of 12 electrodes plus ECG and respiration monitoring in infants, and systematic sleep recording up to age 5 years to capture developmental patterns and epileptiform activity that may only appear during sleep. 1

Technical Requirements by Age

Equipment and Electrode Placement

• Minimum 12 EEG electrodes required in infancy, along with ECG and respiration recording 1
• Surface EMG recording is necessary in epileptology cases to characterize seizure types and refine epilepsy syndrome diagnosis 1
• Continuous head localization (CHL) should be applied during recordings to account for movement 2
• Recording sampling rates typically include 600Hz for standard recordings and 4000Hz for high-resolution analysis 2

Age-Specific Considerations

• Sleep recording is mandatory up to age 5 years for three critical reasons: assessment of brain maturation, reduction of movement artifacts during wakefulness, and capture of sleep-specific grapho-elements essential for diagnosis 1
• Examination timing should align with the child's usual nap schedule, potentially after sleep deprivation to facilitate sleep onset 1
• Grapho-elements and spatio-temporal EEG organization vary significantly with age, requiring interpretation by physicians experienced in pediatric EEG 1

Clinical Applications

Diagnostic Uses

• Seizure evaluation: EEG is recommended as part of the neurodiagnostic evaluation for all children with apparent first unprovoked seizure 3
• Altered mental status assessment: Point-of-care EEG (pocEEG) aids in evaluating altered mental status in emergency settings, with abnormal findings detected in 45% of recordings 4
• Nonconvulsive status epilepticus (NCSE) detection: NCSE can only be diagnosed by EEG, making it essential when standard clinical examination is insufficient 4

Emergency Department Applications

• Point-of-care EEG is feasible in pediatric emergency departments using simplified two-channel setups 4
• Seizure activity is recorded in approximately 16% of emergency pocEEG cases, predominantly in patients with pre-existing neurological conditions 4
• pocEEG influences 60% of clinical decisions by guiding antiseizure medication adjustments in active status epilepticus and identifying NCSE 4

Prognostic Applications

Post-Cardiac Arrest

• EEGs performed within the first 7 days after pediatric cardiac arrest may be considered for prognostication but should not be used as the sole criterion (Class IIb recommendation) 5
• Continuous and reactive EEG tracings within 7 days post-arrest are associated with significantly higher likelihood of good neurologic outcome at hospital discharge 5
• Discontinuous or isoelectric EEG patterns correlate with poorer neurologic outcomes 5
• Multiple variables must be used when attempting to prognosticate outcomes; no single factor predicts outcome with sufficient accuracy (Class I recommendation) 5

Brain Death Determination

• Two examinations are required irrespective of ancillary study results, with different attending physicians performing each exam 5
• Age-dependent observation intervals:
  • Term newborn (37 weeks gestation) to 30 days: 24 hours between exams 5
  • 31 days to 18 years: 12 hours between exams 5
• EEG showing electrocerebral silence (ECS) can reduce observation periods between examinations 5
• In children >30 days, EEG and cerebral blood flow studies have equal sensitivity (89% diagnostic yield for absent cerebral blood flow, 76% for ECS on first study) 5
• EEG is less sensitive in newborns (37 weeks to 30 days), where cerebral blood flow studies may be preferred 5

Common Pitfalls and Caveats

Technical Challenges

• Pediatric EEG contains more artifact contamination than adult recordings due to shorter recording periods and increased movement 6
• Medication effects can significantly influence EEG findings and must be considered during interpretation 5
• Normal variants and unusual EEG aspects are quite wide for any given age, requiring experienced interpretation 1

Clinical Interpretation

• Processed EEG (bispectral index) algorithms are based on adult patients and have not been validated in children of varying ages and brain development 5
• While BIS readings correspond well with propofol sedation depth, the numerical correlations may not be reliable across all pediatric age groups 5
• Concordance between point-of-care EEG and standard EEG is approximately 68%, with 8% of abnormalities normalizing before standard EEG can be performed 4

Prognostic Limitations

• No single EEG feature has perfect predictive value for unfavorable outcomes after cardiac arrest 5
• EEG patterns during therapeutic hypothermia (32°C-34°C) have the same prognostic significance as those during normothermia 5
• Children with more severely abnormal EEG backgrounds tend to have worse outcomes, with each incrementally worse background score increasing odds of death by 3.6-fold 5

Specialized Applications

Epilepsy Surgery Evaluation

• Ictal MEG onset source localization combined with interictal MEG improves identification of seizure onset zones compared to interictal data alone 2
• In 63% of pediatric epilepsy surgery candidates, ictal MEG onset sources are concordant with interictal sources but closer to the actual seizure onset zone defined by intracranial EEG 2

Broader Clinical Utility

• qEEG functional neuroimaging provides additional clinical information for headaches, tics, autism spectrum disorder, inattention, sleep dysregulation, anxiety, and depression 7
• The technique offers high temporal resolution (milliseconds) and improving spatial resolution (down to 3mm³) 7