Download - 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

• 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


• Continuity







• EEG activity asynchronous till 28 weeks CA

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


• Continuity







• 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


• Continuity







• 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


• Continuity







• 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


• Continuity







• 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


• Continuity







• 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 …


• Continuity







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