neonatal eeg patterns

Neonatal EEG

Dr. Rahul Kumar

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

• Activity discontinuous in early life

• Long periods of electrical silence

• Presen in both sleep and awake records

• Seen till 30th week CA

• This pattern is referred to as ‘Trace Discontinua’

• EEG activity becomes continuous during waking by 34 weeks CA

• EEG activity becomes continuous during NREM by 37 weeks CA

• However, semi-periodic, voltage attenuation still seen during NREM sleep, lasting for 10-15 seconds

• Present upto 5-6 weeks of age

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

• EEG activity asynchronous till 28 weeks CA

• Degree of asynchrony decreases with age, mature brain has minimal asynchrony

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

• Beta-delta waveforms are composed of random wave forms

• 0.3-1.5 Hz frequency, superimposed on fast frequency

• Fast frequency in two frequency bands

• 8-12 Hz and 18-22 Hz

• Voltage <75

• Also known as spindle delta bursts, ripples of prematurity, etc

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

• Appear by 26 weeks CA

• 4.5-6 Hz, 20-200 µv

• Occur independently for short bursts, <2 sec

• Expressed maximally at 30-32 weeks CA, then decline in frequency

• Used to determine CA, replaced by alpha rhythm

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

• Bilaterally synchronous

• Present from 35 week CA, up to 44 weeks, till 6weeks post term

• 50-150 µv

• Resemble vertex sharp waves

Parameter Normal Abnormal

Amplitude 50-150 µv > 150 µv

Duration <100 msec >150 msec

Initial Polarity Surface negative Surface positive or negative

Phase Mono or diphasic Polyphasic

Occurrence Random, bilateral, Sleep Runs, 1Hz, unilateral, awake

Following slow wave Absent Present

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

• Response easily identifiable by 37 weeks CA

• Generalised attenuation or rarely augmentation of voltage to loud sounds seen by 34th week

• If background is high voltage delta, response is attenuation

• If background is low voltage theta, response is augmentation

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

• Distinction clear by 36th week CA

• Till that age, Beta Delta complexes dominate

• These change to random, semi arrhythmic activity at 4-8 Hz

• Trace alternans seen during 36-38 weeks

Summary …

Road Map for the Session

• Continuity

• Inter-hemispheric Synchrony

• Beta-Delta Complexes

• Temporal Theta Bursts

• Frontal Sharp Waves

• Reactivity to Stimulus

• Differentiation between sleep and awake eeg

1 sec

50 V

Fp1-A1

Fp2-A2

C3-A1

C4-A2

T5-A1

T6-A2

O1-A1

O2-A2

Hypnagogic Hypersynchrony

34Roffwarg, Muzio, and Dement. Science, 1966