Diese Präsentation wurde erfolgreich gemeldet.
Wir verwenden Ihre LinkedIn Profilangaben und Informationen zu Ihren Aktivitäten, um Anzeigen zu personalisieren und Ihnen relevantere Inhalte anzuzeigen. Sie können Ihre Anzeigeneinstellungen jederzeit ändern.

EEG in neurology and psychiatry

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

  • Loggen Sie sich ein, um Kommentare anzuzeigen.

EEG in neurology and psychiatry

  1. 1. EEG in Neuropsychiatry Presentor- Dr. Kapil Kulkarni Moderator- Dr. J.P. Rawat Jagjivan Ram Railway Hospital, Mumbai Central
  2. 2. 2 KAPIL S KULKARNI
  3. 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. 4. Historical review 4
  5. 5. RECORDINGS FROM ANIMAL BRAIN • First person to record electrical activity from animal brain in 1874. RICHARD CATON , 1874 5
  6. 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. 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. 8. How EEG recording practically done? 8
  9. 9. 9
  10. 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. 11
  12. 12. SURFACE RECORDING BRAIN 1 2 3 R RECORDING 12
  13. 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. 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. 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. 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. 17. What are normal EEG waves? 17
  18. 18. Normal EEG 18
  19. 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. 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. 21. Effect of eye closure 21
  22. 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. 23. NORMAL DELTA ACTIVITY Not present in normal awake EEG Prominent in normal deeper stage of sleep. A frequency of < 4 Hz. 23
  24. 24. NORMAL GAMMA WAVE 24
  25. 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. 26. Referral (Ipsilateral ear) Bipolar EFFECT OF MONTAGE ON AMPLITUDE 26
  27. 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. 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. 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. 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. 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. 32. • Non-invasive • Low cost ADVANTAGES OF EEG 32
  33. 33. What are normal EEG changes according to age ? 33
  34. 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. 35. What are normal EEG changes in sleep? 35
  36. 36. • Sleep uncovers epileptiform activities. • Normal sleep activities also simulates abnormal activities. 36
  37. 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. 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. 39
  40. 40. ALFA DRIFTING INTO THETA STAGE I 40
  41. 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. 42. POSTS during Stage I sleep 42
  43. 43. Drowsiness/ drop out alpha & POSTS Sleep Awake 43
  44. 44. • 12-14Hz, slowed with ↑sleep • Waxing & waning • Location: fronto cental • Origin: Deep frontal & thalamus SLEEP SPINDLES 44
  45. 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. 46. Sleep spindle/Vertex sharp wave 46
  47. 47. • Stage II-IV sleep • Frontocentral • Initial sharp (biphasic)→ slow (1000ms) → fast activities • Appear by 5months of age K- COMPLEX 47
  48. 48. K- Complex/ sleep spindle 48
  49. 49. Arousal rhythm Series of K- complex Normal awake pattern 49
  50. 50. Arousal in moderate sleep 50
  51. 51. Stage II or III sleep 51
  52. 52. What are common variations in EEG ? 52
  53. 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. 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. 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. 56. MORPHOLOGY OF SPIKES Morphologically spikes are of mainly three types: Mono-phasic Bi-phasic Tri-phasic Poly-phasic 56
  57. 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. 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. 59
  60. 60. SPIKE AND WAVE COMPLEX 60
  61. 61. 3 Hz SPIKE n WAVE 61
  62. 62. POLYSPIKES 62
  63. 63. SLOW WAVES 63
  64. 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. 65. PAROXYSMAL EEG ACTIVITY 65
  66. 66. What are clinical uses of EEG ? 66
  67. 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. 68. GENERALIZED TONIC CLONIC SEIZURE 68
  69. 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. 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. 71. SIMPLE PARTIAL SEIZURE 71
  72. 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. 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. 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. 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. 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. 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. 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. 79. EEG OF SSPE 0.5-3 4-16 sec 79
  80. 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. 81. CREUZFELDT – JAKOB DISEASE 0.5-2 100-300ms 81
  82. 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. 83. HERPES SIMPLEX ENCEPHALITIS 83
  84. 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. 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. 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. 87. FOCAL BRAIN LESION 87
  88. 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. 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. 90. EEG OF A CASE OF ALZHEIMERS DISEASE EEG of Alzheimer's disease showing irregular theta activity. 90
  91. 91. What is role of EEG in psychiatry ? 91
  92. 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. 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. 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. 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. 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. 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. 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. 99. Thank You 99
  100. 100. Hypsarrthemia in Infantile Spasm 100

×