CME Financial Disclosure Statement 9a...focal with right eye deviation and aphasia. LP revealed...

Neurophysiology II - EEG Book 1, Section 8b

Baldwin © 2010

www.BeatTheBoards.com 877-225-8384 1

EEG Basics

Maria Baldwin, MDMaria Baldwin, MD

Assistant Professor, Epilepsy, Department of NeurologyAssistant Professor, Epilepsy, Department of Neurology

Loyola University Medical Center, Maywood, ILLoyola University Medical Center, Maywood, IL

[email protected]@lumc.edu

2

CME Financial Disclosure Statement

I, or an immediate family member including I, or an immediate family member including spouse/partner, have at present and/or have spouse/partner, have at present and/or have had within the last 12 months, or anticipate had within the last 12 months, or anticipate NONO financial interest/arrangement or financial interest/arrangement or affiliation with one or more organizations affiliation with one or more organizations that could be perceived as a real or apparent that could be perceived as a real or apparent conflict of interest in context to the design, conflict of interest in context to the design, implementation, presentation, evaluation, etc implementation, presentation, evaluation, etc of CME activities of CME activities –– Maria Baldwin, MDMaria Baldwin, MD

Outline

�� Normal Awake EEGNormal Awake EEG

�� Normal Sleep EEGNormal Sleep EEG

�� Epileptic ActivityEpileptic Activity

�� FocalFocal

�� GeneralizedGeneralized

�� EncephalopathiesEncephalopathies

�� PLEDSPLEDS

�� Burst SuppressionBurst Suppression

Basic EEG


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EEG Frequency And Amplitude

•• FrequenciesFrequencies

��Beta: 13Beta: 13--22Hz22Hz

•• Enhanced with Enhanced with

benzodiazepinesbenzodiazepines

��Alpha: 8Alpha: 8--12Hz12Hz

•• Normal frequency Normal frequency

for adultsfor adults

��Theta: 5Theta: 5--7Hz7Hz

��Delta: 2Delta: 2--4Hz4Hz

�� AmplitudeAmplitude

�� Normal:Normal:

�� High:High:

�� Low:Low:

Alpha Frequency (8-12 Hz)

Isley M. Electromyography/electroencephalography. SpaceLabs Medical, Washington 1993

Beta Frequency (13-22 Hz)


Theta Frequency (5-7 Hz)



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Delta Frequency (2-4 Hz)


Normal Awake EEG

�� Posterior dominant rhythm is seen.Posterior dominant rhythm is seen.

�� Sinusoidal appearanceSinusoidal appearance

�� Frequency: predominantly alpha Frequency: predominantly alpha


Normal Awake EEG

Blume W, Kaibara M, Young G. Atlas of Adult Electroencephalography. 2nd edition. Lippincott Williams and Wilkins, Philadelphia 2002

Normal Awake EEG

with Eye Opening



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Eye Blinks


Eye Movements


Sleep EEG

�� ReviewReview

��Can identify all stages of sleep from EEG based Can identify all stages of sleep from EEG based

on:on:

��Drop out of posterior dominant rhythmDrop out of posterior dominant rhythm

��Appearance of various waveforms such as the vertex Appearance of various waveforms such as the vertex

wave, spindles, kwave, spindles, k--complexes.complexes.

��Changes in amplitudeChanges in amplitude

��Changes in frequencyChanges in frequency

Sleep EEG

�� Stage IStage I�� Dropout of posterior Dropout of posterior

dominant alpha rhythmdominant alpha rhythm

�� Vertex waves appear in the Vertex waves appear in the midlinemidline

�� Body movementBody movement

�� Stage IIStage II

�� Delta/theta slowing seen Delta/theta slowing seen <25%<25%

�� Vertex waves, sleep Vertex waves, sleep spindlesspindles


�� Stage IIIStage III�� >25% delta, <50% delta>25% delta, <50% delta

�� High amplitude High amplitude background, >70uvbackground, >70uv

�� Sleep spindles, KSleep spindles, K--complexescomplexes


�� Stage IVStage IV

�� >50% delta slowing>50% delta slowing

�� Few KFew K--complexescomplexes

�� High amplitude >70uVHigh amplitude >70uV



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Sleep EEG

�� REMREM

��Rapid eye movementsRapid eye movements

��No body movementNo body movement

��Saw tooth waves on EEGSaw tooth waves on EEG

��Low amplitude backgroundLow amplitude background

��Alpha frequencyAlpha frequency

��Prominent in the newborn!!Prominent in the newborn!!

��Decreases in the elderlyDecreases in the elderly

Sleep Vertex Waves


Sleep-Sleep Spindles


Sleep EEG

�� Stage IStage I

Blume W, Kaibara M, Young G. Atlas of Adult Electroencephalography. 2nd edition. Lippincott Williams and Wilkins,Philadelphia 2002


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Sleep EEG

�� Stage IIStage II


Sleep EEG

�� Stage IIIStage III


Sleep EEG

�� Stage IVStage IV


Sleep EEG

�� REMREM



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Disorders of Sleep

�� NonNon--REM disordersREM disorders

�� Night terrorsNight terrors

�� Childhood onsetChildhood onset

�� Awakens with frightAwakens with fright

�� Autonomic symptomsAutonomic symptoms

�� Can’t remember eventsCan’t remember events

�� SonnambulismSonnambulism

�� Eyes openEyes open

�� Perform complex tasksPerform complex tasks

�� No recollection of eventNo recollection of event

Sleep Disorders

�� REM disordersREM disorders

��NightmaresNightmares

��Adults and childrenAdults and children

��Vivid unpleasant dreamsVivid unpleasant dreams

��Rare autonomic symptomsRare autonomic symptoms

��Can remember eventsCan remember events

��REM behavior disorderREM behavior disorder

��Violent behavior during REM sleepViolent behavior during REM sleep

�� Injuries frequentInjuries frequent

��Can see in DementiasCan see in Dementias

Sleep Apnea

�� Diagnose with a polysommnogram!!Diagnose with a polysommnogram!!

�� Obstructive Sleep ApneaObstructive Sleep Apnea�� No airflowNo airflow

�� Abdominal/thoracic respiratory effortAbdominal/thoracic respiratory effort

�� Paradoxical breathingParadoxical breathing

�� Central Sleep ApneaCentral Sleep Apnea�� No airflowNo airflow

�� No abdominal/thoracic effortNo abdominal/thoracic effort

�� Etiology is dysfunction in the brainstem (medulla oblongata)Etiology is dysfunction in the brainstem (medulla oblongata)

�� Mixed Sleep ApneaMixed Sleep Apnea�� Both obstructive and central qualities.Both obstructive and central qualities.

Narcolepsy

�� Diagnose with a Multiple Sleep Latency Diagnose with a Multiple Sleep Latency

Test (MSLT)Test (MSLT)

��Irresistible desire to sleep Irresistible desire to sleep

��Sleep paralysisSleep paralysis

��CataplexyCataplexy

��Hypnagogic hallucinationsHypnagogic hallucinations

��Sleep onset during MSLT test is <5minutes and Sleep onset during MSLT test is <5minutes and

is usually REM onset sleepis usually REM onset sleep


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Abnormal Activity

Interictals, Seizures, Interictals, Seizures,

Encephalopathies/SlowingEncephalopathies/Slowing

And PLEDSAnd PLEDS

Abnormal Activity

�� Categorize based on location/focalityCategorize based on location/focality

��FocalFocal--usually implies structural defectusually implies structural defect

��SlowingSlowing

�� InterictalsInterictals

��Epileptic activityEpileptic activity

��GeneralizedGeneralized

��SlowingSlowing--seen in encephalopathies seen in encephalopathies

�� InterictalsInterictals

��Epileptic activityEpileptic activity

Abnormal Activity

�� SlowingSlowing

��FocalFocal--see with structural deficits or post ictalsee with structural deficits or post ictal

��GeneralizedGeneralized--see in encephalopathiessee in encephalopathies


Abnormal Activity

�� Interictal Activity or Epileptiform ActivityInterictal Activity or Epileptiform Activity

�� “distinctive waves or complexes distinguished from “distinctive waves or complexes distinguished from

background activity and resembling those recorded in a background activity and resembling those recorded in a

portion of human subjects suffering form epileptic portion of human subjects suffering form epileptic

disorders.”disorders.”

�� Sharp waves, Spikes, Spike and wave, polyspike and Sharp waves, Spikes, Spike and wave, polyspike and

wave, etc.wave, etc.

�� Don’t Confuse with Don’t Confuse with epilepticepileptic--pertaining to a seizure.pertaining to a seizure.


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Sharps and Spikes

�� Sharp wavesSharp waves--less than less than

200msec but greater 200msec but greater

than 70ms than 70ms

�� SpikesSpikes--less than 70msless than 70ms

Focal Spikes with Phase Reversal


Generalized Spike and Wave


Generalized Spike and Wave

This is an EEG of a kid with absence seizures! 3Hz spike and wave!Blume W, Kaibara M, Young G. Atlas of Adult Electroencephalography. 2nd edition. Lippincott Williams and Wilkins, Philadelphia 2002


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Abnormal Activity

�� SeizureSeizure

��Abnormal electrical discharge that breaks from Abnormal electrical discharge that breaks from

the background. the background.

��Must change in frequency, amplitude and Must change in frequency, amplitude and

morphology. morphology.

��Should last greater than 10Should last greater than 10--15 seconds.15 seconds.

Seizure

Abnormal Activity

�� EncephalopathyEncephalopathy

��Based on background frequencyBased on background frequency

��DeltaDelta--<4 Hz Severe slowing, “Marked <4 Hz Severe slowing, “Marked

encephalopathy”.encephalopathy”.

��ThetaTheta--44--8Hz Moderate slowing. “Moderate to Mild 8Hz Moderate slowing. “Moderate to Mild

Encephalopathy”.Encephalopathy”.

��AlphaAlpha--88--12 Hz, “Normal”12 Hz, “Normal”

��BetaBeta>13 Hz, excessive beta can be seen with >13 Hz, excessive beta can be seen with

benzodiazepine use.benzodiazepine use.

Encephalopathy

�� Multiple etiologiesMultiple etiologies--infectious, metabolic, infectious, metabolic,

toxic, drug. toxic, drug.

�� Lose posterior dominant rhythmLose posterior dominant rhythm

�� Important to compare from previous Important to compare from previous

recordingsrecordings

�� Can see sleep complexesCan see sleep complexes

�� Reactivity!!!Reactivity!!!


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Moderate Encephalopathy

Theta Frequency


Severe Encephalopathy

Delta Frequency


Encephalopathy

�� FIRDAFIRDA--Frontal Intermittent Rhythmic Delta ActivityFrontal Intermittent Rhythmic Delta Activity

�� Frequently seen in encephalopathiesFrequently seen in encephalopathies


Encephalopathy

�� Triphasic WavesTriphasic Waves

�� Broad sharp waves of a particular morphologyBroad sharp waves of a particular morphology

�� Frequently “negative, positive, negative.Frequently “negative, positive, negative.

�� See in hepatic and uremic encephalopathySee in hepatic and uremic encephalopathy



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Encephalopathy

�� ReactivityReactivity

��If EEG not reactive must be concerned for If EEG not reactive must be concerned for

coma state. coma state.

��Pt must be stimulated during EEGPt must be stimulated during EEG

��Describe coma based on the EEG patternDescribe coma based on the EEG pattern

�� Ie: spindle coma, alpha coma, beta coma, theta Ie: spindle coma, alpha coma, beta coma, theta

coma.coma.

Example of Reactivity

Pinch Pt


Example of Spindle Coma


Abnormal EEG

�� PLEDSPLEDS--Periodic Lateralizing Epileptiform Periodic Lateralizing Epileptiform

DischargesDischarges

��An EEG pattern of sharp waves, spikes or more An EEG pattern of sharp waves, spikes or more

complex patterns that occur at periodic intervals of complex patterns that occur at periodic intervals of

11--2 seconds. 2 seconds.

��Must have return of background between discharges.Must have return of background between discharges.

��Should persist through much of the recording.Should persist through much of the recording.

��Seen with an acute and severe brain insultSeen with an acute and severe brain insult


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PLEDSPLEDS

Post AVM Repair and Stroke

Variant of PLEDs

�� GPEDsGPEDs--Generalized Periodic Lateralizing DischargesGeneralized Periodic Lateralizing Discharges

�� Usually has a worse prognosis than PLEDSUsually has a worse prognosis than PLEDS

�� Commonly seen in CJD, (CrueztfeldCommonly seen in CJD, (Crueztfeld--Jacob Disease)Jacob Disease)

52

Variant of PLEDs

�� GPEDsGPEDs

�� Can also see in the setting of Can also see in the setting of subacutesubacute sclerosingsclerosing

panencephalitispanencephalitis (SSPE).(SSPE).

Cobb, W.1966. The periodic events of subacute sclerosing leucoencephalitis. Electroencephalogr. Clin. Neurophysiol. 21:278-294.


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Abnormal EEG

�� Burst SuppressionBurst Suppression�� No EEG activity/suppression of activity between No EEG activity/suppression of activity between

bursts (<10uv)bursts (<10uv)

�� Bursts can be normal EEG waveforms or Bursts can be normal EEG waveforms or epileptiformepileptiform

�� Periods of suppression should be measured and Periods of suppression should be measured and length and morphology of the bursts should be length and morphology of the bursts should be examined.examined.

�� Can see in SEVERE brain injury, hypothermia and Can see in SEVERE brain injury, hypothermia and drug overdose, drug induced coma (pentobarb).drug overdose, drug induced coma (pentobarb).

Burst Suppression

Question 1

�� Normal awake adult EEG background Normal awake adult EEG background

frequency should be?frequency should be?

��(A) 20(A) 20--30Hz30Hz

��(B) 5(B) 5--7 Hz7 Hz

��(C) 2(C) 2--4 Hz4 Hz

��(D) 8(D) 8--13 Hz13 Hz

Answer 1

�� (D) Normal awake adult background (D) Normal awake adult background

frequency is in the alpha range of 8frequency is in the alpha range of 8--13Hz. 13Hz.


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Question 2

�� Sleep spindles are generated in which part Sleep spindles are generated in which part

of the brain?of the brain?

��(A) Left temporal lobe(A) Left temporal lobe

��(B) Cerebellum(B) Cerebellum

��(C) Thalamus(C) Thalamus

��(D) Medulla (D) Medulla

Answer 2

�� (C) Sleep spindles are generated in the (C) Sleep spindles are generated in the

thalamus and occur prominently during thalamus and occur prominently during

stages 2 and 3 of sleep. stages 2 and 3 of sleep.

Question 3

�� 42 year old right handed male (otherwise healthy, with no 42 year old right handed male (otherwise healthy, with no PMH) presents with new onset seizure after 1 day of “odd PMH) presents with new onset seizure after 1 day of “odd behavior” by his cobehavior” by his co--workers. Seizure clinically appeared workers. Seizure clinically appeared focal with right eye deviation and aphasia. LP revealed focal with right eye deviation and aphasia. LP revealed mildly elevated wbc count and an increased number of mildly elevated wbc count and an increased number of rbcs. EEG showed a periodic lateralizing epileptiform rbcs. EEG showed a periodic lateralizing epileptiform discharges arising from the left temporal lobe. What discharges arising from the left temporal lobe. What infection would you most likely consider in this patient?infection would you most likely consider in this patient?

�� (A) Bacterial meningitis(A) Bacterial meningitis

�� (B) Tuberculosis meningitis(B) Tuberculosis meningitis

�� (C) Herpes encephalitis(C) Herpes encephalitis

�� (D) CMV encephalitis(D) CMV encephalitis

Answer 3

�� (C) Herpes encephalitis clinically presents (C) Herpes encephalitis clinically presents

with altered mental status and focal with altered mental status and focal

seizures. CSF findings show an elevated seizures. CSF findings show an elevated

wbc and rbc count. EEG frequently reveals wbc and rbc count. EEG frequently reveals

focal discharges from the temporal lobes focal discharges from the temporal lobes

and many times a periodic lateralizing and many times a periodic lateralizing

epileptiform discharge (PLED) pattern.epileptiform discharge (PLED) pattern.

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