1. Amplitude integrated EEG (aEEG) is a device that measures background brain activity through electrodes placed on the scalp. It provides information on global brain function through a compressed timescale display. 2. aEEG is useful for predicting outcomes in conditions like hypoxic ischemic encephalopathy, seizures, and neurological disorders. Abnormal aEEG patterns correlate with adverse outcomes while return of normal patterns indicates better prognosis. 3. aEEG can help identify infants who benefit most from therapeutic hypothermia for hypoxic ischemic encephalopathy. More severe abnormalities on aEEG, like burst suppression, are associated with poorer response to cooling therapies.

1. Amplitude integrated EEG
Dr Bhupendra Kumar Gupta
DM resident
Dept of Neonatology
IPGME&R SSKM Hospital
Kolkata

2. Introduction
• Cerebral Function Monitor (CFM) or
amplitude integrated EEG  device used to
measure background electro cortical activity
in the brain.
• The cerebral function monitor provides
information on global cerebral activity
• CFM technology was initially developed in the
1960s for adults suffering from neurological
injury

3. .
• CFM technology was introduced in
neonatology in the mid 1980s .
• It has predictive value on acute neurological
conditions and long term neurodevelopmental
outcome.
• It is also a valuable detection tool for clinical
or subclinical seizures.

4. Indications
• Hypoxic Ischemic Encephalopathy
• Seizures or clinical scenario mimicking seizure
disorders
• Significant neurological disorders (congenital
brain malformations, vascular lesions)
• Post cardiac arrest
• Inborn error of metabolism ( urea cycle
disorders)

5. Principle of CFM
• It involves either a single-channel recording
obtained from one pair of biparietal
electrodes or a dual-channel recording from
two pairs of electrodes one pair for each
hemisphere.
• The EEG signal is filtered to attenuate activity
lower than 2 Hz and higher than 15 Hz (to
minimize artefacts).

6. .
• The signal is rectified and further processed
before being displayed on a modified
semilogarithmic scale at a relatively
compressed time scale.
• The signal is displayed on an x-y axis using a
very slow chart speed (6 cm/h).
• It is possible to select areas of recording and
display the corresponding, expanded raw EEG
trace, which is useful for confirming possible
seizure activity

7. .

8. Applying electrodes
• Biparietal is the optimal location
• This is the watershed area between the
posterior and middle cerebral arteries.
• This area is least likely to be affected by scalp
muscle activity and eye-movement artefacts

9. .

10. .
• Silver chloride disc electrode,hydrogel
electrodes  used on scalp (biparietal)
requires cleaning to assure adequate
adherence.
• Needle electrodes Insert sub-dermally in
parietal position
• Impedance Measures quality of electrode
contact and should be as low as possible.
• High impedance may be caused by poor
electrode contact, electrical, mechanical noise

11. Interpretation
• Amplitudes
• Presence of Sleep/Wake cycle
• Variability — narrow or broad trace.
• Brain Activity Continuous/Discontinuous
• Presence of seizure

12. .
• AmplitudesBand
Width  Top and
bottom border of the
central band of the
trace
• Measured In micro volt.

13. Sleep /wake cycle (SWC) Smooth sinusoidal variation mostly
in lower margin
• Broader trace
bandwidth represent
discontinuous
background activity
during quiet sleep
• Narrow bandwidth
corresponds to more
continuous activity
during wakefulness and
active sleep

14. .
• SWC can be clearly identified as early as 30
weeks gestation and is indicative of better
short-term outcome in preterm babies.
• This cyclicity is often abolished by sedative
drugs or following cerebral insults
• Early return of sleep wake cycling (SWS) after
an asphyxial insult is also a good prognostic
sign.
• Total sleep wake cycle - 60-90 mins

15. Bandwidth variability
1.Limited bandwidth variability
• At higher voltages indicative of organised
/continuous brain activity
• At lower voltage indicative of severe brain
injury
2.Increased bandwidth variability
discontinuous brain activity
3.Greatly reduced bandwidth variability
indicative of poor background activity

16. .

17. Lower margin variability
• Wavy lower margin variability present
• Straight lower margin  variability absent
• Lower margin variability is determining factor
between a continuous and burst suppression
trace

18. Two methods used for classifying
Amplitude-based
• Normal amplitude
• Moderatly abnormal
amplitude
• Severly abnormal
amplitude
Pattern based
• Continuous normal
voltage
• Discontinous normal
voltage
• Burst suppression
• Continuous low voltage
• Flat trace

19. .
• Normal amplitude: The upper margin of band
of aEEG activity >10 μV and the lower margin
>5 μV
• Moderately abnormal amplitude: The upper
margin of band of aEEG activity >10 μV and
the lower margin ≤5 μV
• Severely abnormal amplitude: The upper
margin of the band of aEEG activity <10 μV
and lower margin <5 μV.

20. Continuous normal voltage (CNV)
• Lower margin > 5 micro
volt (7-10 micro volt)
• Upper margin > 10 micro
volt (10-25 micro volt)
• Bandwidth variability is
limited generally between
5-15 micro volt
• Lower margin variability is
present (lower margin is
wavy)
• .

21. Discontinuous normal voltage (DNV)
• Wide banded pattern
• Lower margin < 5 micro
volt
• Upper margin > 10 micro
volt
• SWC absent
• Bandwidth variability is
increased (>25)
• Lower margin variability is
present ,the lower margin
is wavy
• .

22. .
• Widened trace indicates increased variability
in background brain activity due to
intermittent levels of lower activity

23. Burst Suppression (BS)
• Burst Suppression pattern is indicative of the
brain going through bursts of brain activity
followed by period of suppression which is
referred as inter burst interval ( time between
burst of activity)

24. Burst Suppression (BS)
• Lower margin < 5 micro
volt
• Upper margin > 10
micro volt
• SWC absent
• Bandwidth variability is
increased (>25)
• Lower margin variability
is absent ,the lower
margin is flat
• .

25. Continuous low voltage
• Continuous low voltage is indicative of brain
having most of its activity in very low voltage
range

26. Continuous low voltage
• Lower margin < 5 micro
volt
• Upper margin <10
micro volt
• SWC absent
• Bandwidth variability is
limited (4-8 micro volt)
• Lower margin variability
is absent ,the lower
margin is flat
• ..

27. Flat trace
• Relatively flat trace at
the bottom of the a EEG
scale
• .

28. aEEG at Different Gestational/Post conceptional Ages

29. Important points
• Focal abnormalities in the aEEG may not be
identified because the signal is obtained from
a single channel.
• If the CFM trace looks odd or is not consistent
with the clinical picture use the EEG display
facility on the CFM to check for artefacts.

30. .
• Medications may affect the record.
• Anticonvulsants or sedatives such as
morphine or chloral hydrate may transiently
suppress the CFM record.
• So administration of drugs or other clinical
events should be marked

31. Trouble shooting
Background pattern appear erratic or extremely
elevated
• ECG artifact
• Handling
• Muscle activity
• HFOV
• Status epilepticus

32. Background pattern appear depressed
• Scalp edema
• Electrode placed very closely
• Sedation

33. AMPLITUDE-INTEGRATED
ELECTROENCEPHALOGRAPHY AND
NEONATAL ENCEPHALOPATHY
• Hypoxia,ischemia, or hypoglycemia
• Most of the clinical studies of the CFM have been
carried out in infants with HIE
• Infants with mild HIE  continuous or slightly
discontinuous aEEG with absent cyclicity  good
outcome
• Severe HIE  severely abnormal aEEG
background (low voltage, absent of SWC)  high
risk for adverse outcome (death or severe
handicap)

34. .
• If aEEG background becomes continuous
within the first 24 h  almost 50% chance
that the infant will survive without handicap
• Infants with HIE time of onset and the
quality of SWC is associated with outcome
• Onset of normal SWC within the first 36 h is
associated with normal outcome while infants
with later onset of SWC or abnormal SWC
were more likely to have neurological
handicap

35. .
• Studies have shown that 6 to 12 h of life is the
period during which the aEEG background is
most valuable.
• Sensitivities range from 91% to 100% with
positive predictive values of nearly 85%.
• Both the early aEEG and clinical examination
within the first 12 h of birth increased the PPV
and specificity compared with either method
alone

36. .
• A burst suppression pattern, continuous low
voltag or flat trace persisting beyond 24–36
hours indicates a high probability of an
abnormal neurodevelopmental outcome at
18–24 months

37. Therapeutic hypothermia
• The aEEG was used to help the selection of
patients in the Cool Cap trial of selective head
cooling
• In the sub analysis, those infants with
evidence of moderate encephalopathy on
aEEG ( a discontinuous pattern) benefited
from hypothermia

38. .
• severe encephalopathy ( burst suppression,
continuous low voltage or flat trace) on aEEG
did not show significant benefit.
• Selective head cooling was found to decrease
the risk of death or severe
neurodevelopmental disability at 18 months
of age

39. .
• The total body hypothermia for neonatal
encephalopathy (TOBY) trial also used aEEG
for entry criteria in subject selection to receive
cooling therapy.
• More of those infants with severe abnormal
aEEG died or had a severe disability than
those of with moderately abnormal aEEG
traces

40. Seizure
• Characterized by sudden rise in the lower margin
sometimes accompanied by a rise in the upper
margin
• Rhythmic discharges on the raw EEG
• Seizures may only be identified if they are
sufficiently prolonged, more than 2-3 minutes.
• Shorter lasting discharges may be missed since
the CFM is recorded at a very slow speed.

41. .

42. .
• Digital aEEG monitors that provide one or
two-channel of raw EEG with the aEEG trace
have been shown to detect 80% of all
electrographic seizures in the newborn.

43. Conclusion
• The use of aEEG has proved to be of clinical
value in sick neonates
• aEEG should be used as a complement to EEG
in high risk infants in NICU.
• The aEEG trace in term infants with newborn
encephalopathy is sensitive and specific for
early prediction of later neurodevelopmental
outcomes

44. References
• Atlas of amplitude-integrated EEGs in the
newborn
• Volpe’s neurology of newborn
• Neo reviews

45. .
Thank you