This presentation gives basic account of characteristic EEG patterns seen in common psychiatric and neurological conditions.

1. EEG in Neuropsychiatry
Presentor- Dr. Kapil Kulkarni
Moderator- Dr. J.P. Rawat
Jagjivan Ram Railway Hospital,
Mumbai Central

2. 2
KAPIL S KULKARNI

3. What is EEG ?
• EEG (Electroencephalogram) refers to recording and analysis
of electrical activity of brain recorded by amplifying voltage
differences between electrodes placed on scalp or cerebral
cortex .
• This electrical potential is produced by excitatory or inhibitory
post synaptic electrical discharges from neuronal dendrites at
cortical surfaces.
• Such neurons constitute only 5% of total neurons of the brain.
• Voltage recorded on EEG is only 10% of the voltage recorded
on ECG due to high resistance of skull.
3

4. Historical review
4

5. RECORDINGS FROM ANIMAL BRAIN
• First person to record electrical
activity from animal brain in
1874.
RICHARD CATON , 1874 5

6. RECORDING FROM HUMAN BRAIN
• First recording from human
scalp in 1924.
• Report published in 1929
• Danis William started clinical
use to localize brain trauma
during ww II in oxford.
HANS BERGER 1924 6

7. Hans Berger 1835-1911: Human EEG
Prof of Psychiatry, University of Jena
Germany, Removed from job in one
day notice by the Nazis, committed
suicide
Berger wave
7

8. How EEG recording practically done?
8

9. 9

10. • Standard 10-20 International Electrode Placement System.
• Total 21 electrodes.
• Odd number left & even number on right side.
• Electrodes- Silver/gold/steel. • Fp1,2= prefrontal
• F3,4=frontal
• C3,4=central
• P3,4=parietal
• O1,2=occipital
• F7,8=ant.-temporal
[placed on frontal
bone]
• T3,4=mid-temporal
• T5,6-=post.-
temporal
• A1,2=ear, mastoid
• Fz=Frontal midline
• Cz=Central vertex
• Pz=parietal midline
10

11. 11

12. SURFACE RECORDING
BRAIN
1
2
3
R
RECORDING
12

13. • Montage refers to the particular combination of electrodes
examining at a particular point of time.
• When a single reference point is used for all electrodes 
Referential montage.
• When several referential points are used for recording  Bipolar
montage.
• In bipolar montage the electrodes form a chain passed side by side
or front to back.
MONTAGE
13

14. REFERENCE MONTAGE • Connects active
scalp electrodes
and an inactive
electrode placed
away from the
scalp e.g. on ear,
nose or chin
[Reference
electrode]
– Disadvantage
with ear-
some brain
activity
– Chin & nose-
heart activity
• Useful for seeing
amplitude of
waves
14

15. BIPOLAR MONTAGE
• Connects two active
scalp electrodes
• Each channel is
attached to two
different electrodes
• Arrangement of
channels in
montages-
– Anteriorly placed
electrodes on
initial channels-
helps see
progression of
waves
– Alternate left and
right electrodes-
helps compare the
two sides
15

16. • Electrodes- 21
• Sensitivity- 5-10 micro volts/mm ( avg 7)
• Paper speed – 3 cm/ sec ( adjustable)
• Length of recording – 2 min each montage
- 30 min awake record (10 min
sleep)
• Activation – Hyperventilation – 3min + 1min
- Photic st -30 cm 10,15,20,30,40 Hz
,each in trains of 10 sec.
STANDARDS
16

17. What are normal EEG waves?
17

18. Normal EEG
18

19.  Found in normal eye
closed EEG
 Highly rhythmic
 Frequency  8 to 13 HZ
 Prominent in the posterior
cortex
 Mainly occipital , temporal
and parietal cortex
NORMAL ALPHA WAVES
19

20. NORMAL BETA WAVE
Frequent in normal
eye open EEG
EEG waves of >13 HZ
Usually of low voltage
Found in frontal and
central region
20

21. Effect of eye closure
21

22. NORMAL THETA WAVES
Small amount of
sporadic and isolated
activity found in normal
awake state
Prominent in drowsy
and sleep EEG tracing
EEG activity of 4 to 7
HZ
 found in frontal and
temporal region
22

23. NORMAL DELTA ACTIVITY
Not present in normal
awake EEG
Prominent in normal
deeper stage of sleep.
A frequency of < 4 Hz.
23

24. NORMAL GAMMA WAVE
24

25. Amplitude
• Measured: peak to peak
• Expressed as range i.e 40-50μv
• Depends on
– Inter electrode distance
– Type of montage
– Type of recording
• surface (10-100 μv)
• Depth 500-1500 μv
25

26. Referral (Ipsilateral ear) Bipolar
EFFECT OF MONTAGE ON AMPLITUDE
26

27. • Hyperventilation - causes cortical hypocapnia-> cerebral
vasoconstriction and hypoxia -> may allow epileptic foci to
become evident
• Photic stimulation - a strobe light flashing at 8-15 Hz is used to
capture the occipital α frequency - α frequency adjusts to
match that of the strobe - may allow epileptic foci to be seen
and may even induce epileptic seizures, as may a flickering
television screen
• Sleep deprivation.
• Sleep EEG
ACTIVATION
27

28. • Depth electrodes
• Ambulatory (24-hour) EEG
• Q-EEG/BEAM/Brain Mapping/rEEG
Multichannel recording of eyes-closed, resting EEG - visually
edited & a sample of artifact-free data, analyzed, using the
Fast Fourier Transform (FFT) to quantify the power at each
frequency of the EEG averaged across the entire sample,
known as the power spectrum.
QEEG findings are then compared to a normative database
This database consists of brain map recordings of several
hundred healthy individuals
Comparisons are displayed as Z scores, which represent
standard deviations from the norm.
EEG TECHNIQUES
28

29. • Absolute power
This refers to the amount of activity within a specific frequency
band of brain waves
• Relative power
This refers to the relative amount of activity within a specific
frequency band compared to all the other frequency bands
• Coherence
Measure of synchronization between activity in two channels
• Symmetry
Ratio of power in each band between a symmetrical pair of
electrodes 29

30. LORETA (Low Resolution Electromagnetic Tomography) -
Complex mathematical calculations to construct a visual image
of the 3D electrical activity of deep parts of the brain from
surface electrical measures
30

31. EEG techniques (continued..)
• Video EEG/Video telemetry- Simultaneous recording of brain
activity on an EEG and behavior on tape or digital video
• ERP - An event-related potential (ERP) is any stereotyped
electrophysiological response to an internal or external
stimulus.
• Polysomnography – Simultaneous recording of EEG, muscle
tone, oculogram, respiration.
31

32. • Non-invasive
• Low cost
ADVANTAGES OF EEG
32

33. What are normal EEG changes
according to age ?
33

34. • At birth up to 6 months – 4 Hz (Delta)
• 6-12 months – 6 Hz (Theta)
• 1-3 yrs – 8 Hz (Alfa coming in)
• 3-11 yrs – 12 Hz (Maturation of Alfa)
34

35. What are normal EEG changes in
sleep?
35

36. • Sleep uncovers epileptiform activities.
• Normal sleep activities also simulates
abnormal activities.
36

37. • NREM sleep
– Stage I- Drowsiness
– Stage II- Light sleep
– Stage III- Deep sleep
– Stage IV- Very deep sleep
• REM sleep (paradoxical sleep)
SLEEP STAGES
37

38. SLEEP CHANGES EEG CHANGES
• NREM
• Stage1-Drowsiness - Alpha drop out,vertex waves, POSTS.
• Stage 2-Light sleep - Spindle,vertex wave, K-complex, theta
activity.
• Stage 3-Deep sleep – Slow wave sleep,K- complexes, Delta
activity starts.
• Stage 4-Very deep sleep - Much slowing ,some K complexes,
delta activity.
• REM sleep - Desynchronization with fast frequencies.
38

39. 39

40. ALFA DRIFTING INTO THETA STAGE I
40

41. • In deep drowsiness, stage I (may persist during
stage II & III)
• 50-80% in normal adults
• Location – occipital
• Monophasic, triangular
• 1Hz (4-6 Hz rare)
POSITIVE OCCIPITAL SHARP TRANSIENT OF SLEEP
(POSTS)
41

42. POSTS during Stage I sleep
42

43. Drowsiness/ drop out alpha & POSTS
Sleep Awake 43

44. • 12-14Hz, slowed with ↑sleep
• Waxing & waning
• Location: fronto cental
• Origin: Deep frontal & thalamus
SLEEP SPINDLES
44

45. • Positive followed by large negative
wave
• May precede or follow smaller waves
of opposite polarity
• Maximum at vertex may extend to
frontal & parietal region
• Bilaterally synchronous
• Appear by 5month, prominent in
youth
• Not suppressed by focal lesion
VERTEX SHARP WAVES
45

46. Sleep spindle/Vertex sharp wave
46

47. • Stage II-IV sleep
• Frontocentral
• Initial sharp (biphasic)→ slow
(1000ms) → fast activities
• Appear by 5months of age
K- COMPLEX
47

48. K- Complex/ sleep spindle
48

49. Arousal rhythm
Series of K- complex
Normal awake pattern
49

50. Arousal in moderate sleep
50

51. Stage II or III sleep
51

52. What are common variations in EEG ?
52

53. AWAY FROM NORMALITY
WAVE EEG
AMPLITUDE SPIKES / SHARP WAVES
RHYTHM SLOW / FAST / PERIODIC DISCHARGES
COMMON IS THE PERMUTATION AND COMBINATION OF THE TWO
53

54. ABNORMAL ACTIVITES
• Spike
• Sharp waves
• Spike – and – wave complexes
• Slow spike – and – wave complexes
• 3-Hz spike – and – wave complexes
• Polyspikes
• Photoparoxysmal response
54

55. SPIKES
It is a transient discharge , clearly distinguished from the
background activity , having pointed peak and duration of 20
to 70 m sec. in conventional paper speed.
The main component is generally negative and amplitude is
variable.
The after coming slow wave is surface negative and depict
long hyper polarization.
Positive waves are common in in depth recording.
Spikes increased after seizure , but not increased prior to
seizure (Gotman 1984)
55

56. MORPHOLOGY OF SPIKES
Morphologically spikes are of mainly three types:
Mono-phasic
Bi-phasic
Tri-phasic
Poly-phasic
56

57. ROLANDIC SPIKES
Misnomer as the total
duration is more than 70 m
sec
Appears as isolated spikes
in centrotemoral region.
In BCECTS
The entire complex
consists of 80 to 120 ms
57

58. SHARP WAVES
• Sharp waves are defined as transient discharges clearly
distinguished from background activity having pointed peak
and at conventional paper speed it has a duration of 70 – 200
m sec.
• The main component is usually negative with ascending
component is sharp but descending component is slow.
58

59. 59

60. SPIKE AND WAVE COMPLEX
60

61. 3 Hz SPIKE n WAVE
61

62. POLYSPIKES
62

63. SLOW WAVES
63

64. • Abnormal
• Spike : < 70 ms
• Sharp waves : 70 – 200 ms
• Slow waves : > 200 ms
• Alone or in combination
• Focal, multifocal, hemigeneralized, generalized
• Infrequent to continuous
• Periodic
PAROXYSMAL ACTIVITY
64

65. PAROXYSMAL EEG ACTIVITY
65

66. What are clinical uses of EEG ?
66

67. ABRUPT LOSS OF VOLTAGE DUE TO DESYNCHRONYSATION
THERE IS 20 – 40 HZ FAST ACTIVITY
1 - 3 SEC
APPROXIMATELY 10 HZ SPIKE WAVE WITH HIGH AMPLITUDE
APROXIMALTELY 10 SEC
FREQUENCY SLOWS DOWN AND COME TO DELTA RANGE
ONCE 4 HZ REACHED THEN SLOW WAVES INTERUPT THE RECURRING
RHYTHM
IT FOLLOWS THE POST ICTAL FLATNESS
GRADUALLY DETA , ALPHA THE BETA RANGE WAVES RETURNS
GENERALIZED TONIC CLONIC SEIZURE
67

68. GENERALIZED TONIC CLONIC SEIZURE
68

69. ABSENCE SEIZURE
Characteristics are 3 HZ spike
wave complex
Appears and goes of abruptly on
normal background activity
Maximum at frontal and midline
region
Starts at 4 HZ then slows down to
3.5 HZ then up to 2.5 Z
Hyperventilation precipitate such
attacks
Paroxysm of more than 5 sec
leads to clinical seizure69

70. SIMPLE PARTIAL SEIZURE
• Consciousness is fully preserved.
• EEG shows
» Spikes over the involved cortex
» Wide spread desynchronisaton , more or less
theta and delta activity.
» Uninvolved regions shows normal EEG pattern
70

71. SIMPLE PARTIAL SEIZURE
71

72. COMPLEX PARTIAL SEIZURE
•EEG is variable
•Nasopharyngeal and
sphenoiddal electrode is
helpful in recording
•Temporal spikes are
common.
•The EEG may show 4Hz flat
topped waves and 6 Hz flat-
topped waves
72

73. JAPANESE ENCEPHALITIS
It include the diminution of
electrical activity
Slow waves are important
the changes are not
characteristic
It depicts the severity of
the illness
Improvement occurs with
the corresponding
improvement of the EEG
73

74. HEPATIC ENCEPHALOPATHY
Stage consciousness EEG
I Alert Normal
II Drowsy Slow alpha , poorly developed K-
complex and sleep spindle
III Stupor Theta activity , absence of sleep
pattern
IV Coma Tri-phasic wave
V Deep coma Delta wave
VI Deep coma Flat EEG
74

75. EEG of a case of hepatic encephalopathy after vaproate toxicity , fig1 shows diffuse
slowing of activity , fig 2 shows improvement after treatment ( curtsy – international
journal of neurology Feb’ 09)
EEG OF HEPATIC ENCEPHALOPATHY
Fig 1 Fig 2
75

76. DELIRIUM TREMENS
Beta predominance with
spares normal alpha during
acute florid stage
Persistent delta with little
beta and alpha
During recovery the first to
predominant beta with
spares alpha
Those who exhibits
persistent theta suggests
residual brain damage.Beta prominence in the EEG
76

77. PERIODIC DISCHARGE
• Periodic discharges are of high amplitude and it may me spike
or sharp waves and the duration may exceeds 150 m sec and
recurring at periodic interval.
• It may be the most important EEG finding for ongoing CNS
disease or some CNS infections.
• Morphology me be specific for the disease-
• Burst suppression
• Repetitive sharp waves
• Periodic triphasic
• Focal periodic
• Generalized periodic slow waves
77

78. SSPE
Occurs in a minor percentage of cases of measles
virus infection.
1. Periodic discharge dominates the picture.
2. Duration of 0.5 – 3 sec
3. Average of 500 mic volt
4. Every 4 – 16 sec interval
5. Giant slow waves
6. Discharges are mixed
7. Prominent in the vertex
8. There may be accompanying myoclonus
78

79. EEG OF SSPE
0.5-3
4-16 sec
79

80. CREUZFELDT – JAKOB DISEASE
• It is a prion disease.
• The EEG characteristics are as follows:
– In the first stage there is non specific change in the EEG
– In the 2nd stage patient developed
1. Periodic tri-phasic / bi-phasic complexes
2. Duration of 100-300 m.sec
3. Reparation every 0.5 to 2 sec
4. It is most prominent in anterior region
5. Later stages slow waves become prominent
80

81. CREUZFELDT – JAKOB DISEASE
0.5-2
100-300ms
81

82. HERPES SIMPLEX ENCEPHALITIS
• The EEG finding of HSE is highly suggestive (but not
pathogomonic).
• EEG shows-
• Early stage there is focal or lateralized polymorphic
delta activity on same side.
• Slow wave later involve frontotemporal region.
• Sharp slow wave recurring at every 1-5 sec interval.
• The complex comprises of upto1000ms.
• Usually appears with in 2 to 15 days but may appear
after 30 days.
82

83. HERPES SIMPLEX ENCEPHALITIS
83

84. CEREBRAL ANOXIA
On flat back ground
generalized synchronous
repetitive simple or
compound sharp waves.
Associated with
myoclonus.
Occurs with a burst and
suppression burst pattern.
84

85. FOCAL BRAIN LESIONS
• The types of EEG abnormality in focal brain lesions are:
– Abnormal background rhythm
– Focal absence of neuronal activity  tumor area
– Burst suppression pattern  abutting area
– Continuous slow wave  most distal zone
– Arrhythmic focal hemispheric or generalized delta
activity
– Less than 4 HZ delta activity
– Continuous or sporadic
– Destructive lesions  abscess, hematoma are
associated
85

86. FOCAL BRAIN LESION
– Intermittent rhythmic slow activity:
– It may be of theta or delta range
– Independently or mixed
– Infra-tentorial, supra-tentorial or peri-ventricular
tumor.
– Epileptiform activity
– Focal in onset
– Localized hemispheric lesion
– Often accompanied by slowing of activity
86

87. FOCAL BRAIN LESION
87

88. DEGENERATIVE DISEASE
• The EEG change in the degenerative disease is non
specific.
• There was no consistent difference between cortical
or sub-cortical dementia.
• But sub-cortical dementia shows more normal EEG
• Multi-infract condition may show some lateralizing
sign.
88

89. DEGENERATIVE DISEASE
• Alzheimer's disease:
• Initially there was irregular theta activity
• Later become prominent back ground activity
• Lastly delta activity become prominent
• Fronto-temporal dementia :
• EEG remains persistently normal
• Quantitative analysis showed some abnormality
• Huntingtons disease:
• > 10 µv beta activity is characteristic
89

90. EEG OF A CASE OF ALZHEIMERS DISEASE
EEG of Alzheimer's disease showing irregular theta activity. 90

91. What is role of EEG in psychiatry ?
91

92. SCHIZOPHRENIA
• S-EEG findings in schizophrenia is non specific
Widespread slow activity
 Diffuse Dysrhythmia
Spikes or spike-wave complex
• Q- EEG abnormality -extensively examined:
 Extensive slow wave rhythm preponderance
 Delta activity  anterior brain region
 Theta activity  posterior brain region
 Beta activity with small increase in amplitude
92

93. MOOD DISORDER
• Most of the studies suggests-
• Increased beta / alpha power
• Asymmetric increase in alpha / beta activity in left
frontal region
• Less alpha power and higher EEG findings are seen in
subclinical and depressed patients relatives.
• Recently Q-EEG used as the predictor for
antidepressant response.
93

94. ANTISOCIAL AND BORDERLINE PERSOANLITY DISORDER
• Antisocial personality disorder:
• Frequently associated with organic brain pathology.
• Abnormal behavior is frequently but non specific EEG
changes.
• Borderline personality disorder:
• A number of patients subsequently diagnosed as
complex partial seizure.
• 40 – 80 % have back ground slowing of activity.
• ¼ th of cases have 6 to 14 / sec spike activity might be
the correlate of episodic impulsive activity.
94

95. ATTENTION DEFICIT HYPERACTIVITY DISORDER
• 1/3rd had EEG abnormality.
• Pediatric Neurology reports Epiletiform discharges in ADHD
patients.
• Q-EEG showed increased activity in Frontal region.
• But confounding factors denote that learning disability also
shows similar result.
95

96. CONTROVERSIAL WAVE FORMS
RELEVANT TO PSYCHIATRY
• Fourteen and six per second positive spike:
– Age related change in wave form ,
– some psychiatric phenomena are though to be associated,
– etiology presumed to be closed Bain injury or infection.
• Rhythmic mid temporal discharges:
– 1/3rd to ½ patient showed rhythmic mid temporal
discharges
– Associated with anxiety and somatization.
– Some studies demonstrate behavioral discontrol and
autonomic phenomena.
96

97. CONTROVERSIAL WAVE FORMS
RELEVANT TO PSYCHIATRY
• Benign Epiletiform transients of sleep:
• Low-voltage sharp negative or biphasic waves
• some time alternate between right to left hemisphere.
• Associated with vegetative symptoms.
• Six per second spike and wave:
• Also called phantom wave
• Low amplitude waves  difficult to recognize
• Associated with impulsivity and vegetative symptoms.
97

98. Take Home Message
EEG is simple, noninvasive and inexpensive
investigation.
It can be used for screening as well as
predicting outcome of many neurological and
psychiatric disorders.
98

99. Thank You 99

100. Hypsarrthemia in Infantile Spasm
100