3. EEG changes during the perinatal period, infancy,
childhood, and adolescence are concomitant with
brain growth, myelination, expanding
connectivity, and overall maturation, which are
particularly fast during the first year of life.
Along the third trimester of gestation, EEG
gradually evolves from a slow, high-amplitude,
mostly discontinuous, and asynchronous activity
to more continuous, faster, and more synchronous
activity of lower amplitude.
4. Preterm
From 35 PMW, organization into behavioral
states are clearly identifiable:
o Wakefulness W (active and quiet),
o Active sleep AS (precursor of the later
REM sleep),
o Quiet sleep QS (precursor of the later
slow sleep)
5. Active sleep in 34 PMW neonate. Continuous activity with multifocal delta brushes.
6. In QS
o the EEG is discontinuous or semidiscontinuous,
with IBI lasting less than 10s.
o Delta brushes are less abundant.
o The EEG is mostly synchronous between
hemispheres, except during the transition from
active to quiet sleep, where asynchrony
between hemispheres may last for a few
minutes
9. EEG IN THE FULL-TERM NEWBORN
o The full-term newborn falls asleep in AS1, followed by QS and
AS2.
o In contrast to adults who spend only 20% in REM sleep, in the
newborn AS represents 50% of the sleep time with a mean sleep
cycle duration of approximately 70min.
o Only during the transition from active to quiet sleep can
temporary asynchrony be observed for up to several minutes
o Background activity in W and AS consists of “mixed frequencies,”
with continuous, irregular, diffuse activity, mainly in the theta (4–
7Hz) band, sometimes mixed with occipital delta
o Frontal transients
o Anterior slow dysrhythmia
15. In QS (full term neonate)
The background activity is initially
continuous:(diffuse delta waves (1–3Hz) followed
by the trace alternant. It consists of bilateral bursts
of delta waves (1–3Hz) of high amplitude mixed
with continuous theta activity of lower amplitude.
Bursts last 3–8s and alternate with low amplitude
theta activity of mostly the same duration
16. Trace Alternant. Trace alternant begins to wane by 38–40 weeks CA and disappears
by 44–46 weeks CA when it is replaced by continuous slow-wave activity. After that,
sleep spindles present at around 46 weeks CA
17.
18.
19. o The distinction between trace alternant and trace
discontinu is the amplitude of IBI (inter burst
interval). In trace discontinu, it is less than 25 μV,
whereas in trace alternant, it is more than 25 μV.
o Burst suppression is different from trace
discontinu in that it is excessively discontinuous
and invariant and completely unreactive to
noxious stimulation. The IBI contains very low-
voltage (<5 μV) activity that can last more than
20 sec.
o Also, there is no spontaneous cycling of state.
Some patients may have myoclonic jerks during
the bursts. Poor outcome is noted in 85–100%.
20. EEG IN INFANCY (1–12MONTHS)
o Awake, the mixed frequencies activity present in
the neonatal period is gradually replaced by more
rhythmic theta waves with increasing frequency,
ranging from 3–4Hz at 3 months, to 5Hz at 5
months, and 6–7Hz by the end of the first year of
life .
o These rhythms, which precede the occipital alpha
rhythm, are initially located in rolandic occipital
regions and can reach an amplitude of 75mV.
o A visual blocking response is usually present at the
age of 3–4months.
22. o Trace alternant disappears at about 44 PMW and is replaced by
a diffuse polymorphic delta activity in the occipital areas;
o From 2–3months of age to adulthood wakefulness/drowsiness is
followed by slow sleep.
o Sleep spindles usually appear during the second month, with a
maximal amplitude in central or centroparietal regions.
By 6 months of age, spindles are bilateral but may still be
asynchronous.
o Vertex sharp waves and K-complexes usually appear at the age
of 5–6 months
o Hypnagogic hypersynchrony in 3 months to 8 years.
o A gradual decrease of REM sleep occurs along the first year of
life from around 50% at birth, to 40% at 3–5 months and 30%
between 1and 2 years
23. EEG FROM TODDLERS TO ADOLESCENTS
Wakefulness
o The posterior basic rhythm increases from theta frequencies
to lower alpha range (6–7Hz in the second year, 7–9Hz in the third
year) with high interindividual variability; the rhythm is up to 11Hz
at age 10–11 years,
Amplitude asymmetry with higher voltage over the nondominant
hemisphere does not exceed 20%. Eye opening attenuates alpha
rhythm (AR) and eye closure accentuates AR.
AR also attenuates with : Drowsiness, Concentration, Stimulation
Visual fixation, Anxiety, Eye closure with mental calculation
o Beta frequencies can be observed in frontal regions.
o Lambda waves Resemble positive occipital sharp transients of
sleep (POSTS) ,Do not occur before 1 year of age, attenuated by:
Darkening room
Staring at a blank card
Eye closure
27. Sleep
stage II sleep is characterized by sleep spindles become
symmetrical and synchronous with a frequency range of
12–14Hz, Shorter duration with increase the age.
POSTS occur during deep drowsiness and stage 2 sleep.
Rare in REM sleep. Best seen at the age of 15–35 years
and rarely <3 years.
