ean/ilae-cea: how to approach eeg and avoid overreading …4rd congress of the european academy of...

4rd Congress of the European Academy of Neurology

Lisbon, Portugal, June 16 - 19, 2018

Teaching Course 12

EAN/ILAE-CEA: How to approach EEG and avoid overreading in epilepsy - Level 1

What are epileptiform discharges & what do they mean clinically?

Francisco Sales Inácio Coimbra, Portugal

Email: [email protected]

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How to approach EEG and avoid overeading in epilepsy

Francisco SalesComprehensive Epilepsy CenterNeurology DepartmentCentro Hospitalar e Universitário de Coimbra

Disclosure statement

The author has no conflict of interest in relation to this manuscript

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Francisco SalesComprehensive Epilepsy CenterNeurology DepartmentCentro Hospitalar e Universitário de Coimbra

Disclosure statement

The author has no conflict of interest in relation to this manuscript

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Outline:

1. What should we keep in mind before the temptation 2. What are we looking for when evaluating an EEG3. Zoom in Zoom out or the scale effect4. The window effect5. The elephant effect6. How to standardize the way we talk7. Misleading generalized patterns8. Misleading focal patterns

This talk reflects my own conservative view of what should be the interpretation of an EEG

Different level of questions:1.What are the physiological basis of the EEG? OR2.What is the meaning of these discrete sharp

transients.

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Outline:

1. What should we keep in mind before the temptation 2. What are we looking for when evaluating an EEG3. Zoom in Zoom out or the scale effect4. The window effect5. The elephant effect6. How to standardize the way we talk7. Misleading generalized patterns8. Misleading focal patterns

This talk reflects my own conservative view of what should be the interpretation of an EEG

Different level of questions:1.What are the physiological basis of the EEG? OR2.What is the meaning of these discrete sharp

transients.

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https://www.youtube.com/watch?v=h2H6POZowiU

The generator sources for EEG waves result mainly from the effect of spatial and temporal summation of synchronized synaptic activity

1. What should we keep in mind before the temptation

What should we keep in mind before starting

Santiago Ramón y Cajal, 1852 – 1934.John Carew Eccles, 1903 - 1997https://pt.coursera.org/learn/clinical-neurology/lecture/oUImb/module-3-part-1-overview-and-electroencephalography

What should we keep in mind before starting: EEG generators as dipole sources

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https://www.youtube.com/watch?v=h2H6POZowiU

The generator sources for EEG waves result mainly from the effect of spatial and temporal summation of synchronized synaptic activity

1. What should we keep in mind before the temptation

What should we keep in mind before starting

Santiago Ramón y Cajal, 1852 – 1934.John Carew Eccles, 1903 - 1997https://pt.coursera.org/learn/clinical-neurology/lecture/oUImb/module-3-part-1-overview-and-electroencephalography

What should we keep in mind before starting: EEG generators as dipole sources

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The generation of electroencephalogram (EEG) network oscillations. EEG signals are generated by the integration of neural activity at multiple spatial (A) and temporal (B) scales. After Le Van Quyen (2011).Rhythms of the brain, Gyorgy Buzsáki, Oxford University Press 2006

What should we keep in mind before starting: The generation of EEG network oscillations result from the integration of neural activity at multiple spatial and temporal scales. The EEG recorded from scalp samples mostly the synaptic activity that occurs in the superficial layers of the cortex. The contribution of neuronal activity below the cortex is, in most cases, virtually negligible.

To appreciate the differences between the two subdural strip recordings (ECoG) and the EEG scalp (black)

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The generation of electroencephalogram (EEG) network oscillations. EEG signals are generated by the integration of neural activity at multiple spatial (A) and temporal (B) scales. After Le Van Quyen (2011).Rhythms of the brain, Gyorgy Buzsáki, Oxford University Press 2006

What should we keep in mind before starting: The generation of EEG network oscillations result from the integration of neural activity at multiple spatial and temporal scales. The EEG recorded from scalp samples mostly the synaptic activity that occurs in the superficial layers of the cortex. The contribution of neuronal activity below the cortex is, in most cases, virtually negligible.

To appreciate the differences between the two subdural strip recordings (ECoG) and the EEG scalp (black)

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What should we keep in mind before starting: Factors affecting scalp EEG potentials.The window effect: a) frequency bandwidth.

PLoS One. 2016 Jun 24;11(6):e0158276. doi: 10.1371/journal.pone.0158276. eCollection 2016.RIPPLELAB: A Comprehensive Application for the Detection, Analysis and Classification of High Frequency Oscillations in Electroencephalographic Signals.Navarrete M1,2, Alvarado-Rojas C3,4, Le Van Quyen M3, Valderrama M1.

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What should we keep in mind before starting: Factors affecting scalp EEG potentials.The window effect: a) frequency bandwidth.

PLoS One. 2016 Jun 24;11(6):e0158276. doi: 10.1371/journal.pone.0158276. eCollection 2016.RIPPLELAB: A Comprehensive Application for the Detection, Analysis and Classification of High Frequency Oscillations in Electroencephalographic Signals.Navarrete M1,2, Alvarado-Rojas C3,4, Le Van Quyen M3, Valderrama M1.

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A

D

B

C

E

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ECoG recorded by SEEG: gamma activity at SOZ

What should we keep in mind before starting: Factors affecting scalp EEG potentials

Geometry and volume of the generators/dipole

Conductive properties of interveningtissues

Most cortical spikes with extent of < 10 cm2 do not produce a recognizable scalp EEG potential. This may serve a useful role in filtering out all but the most significant spike sources that can recruit substantial surrounding cortex.

James X. Tao, Amit Ray, Susan Hawes-Ebersole, John S. Ebersole. Intracranial EEG Substrates of Scalp EEG Interictal Spikes. Epilepsia, 46(5):669–676, 2005

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A

D

B

C

E

G

F

ECoG recorded by SEEG: gamma activity at SOZ


Geometry and volume of the generators/dipole

Conductive properties of interveningtissues

Most cortical spikes with extent of < 10 cm2 do not produce a recognizable scalp EEG potential. This may serve a useful role in filtering out all but the most significant spike sources that can recruit substantial surrounding cortex.


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Recording technique: Analogue-to-Digital conversion (ADC)

Factors that affect the accuracy of the waveform:

Sampling rate (amplifier characteristics, clinical setting ± 1KHz, research > 10 KHz)

Sampling skew Display - screen resolution (new generation 4K)

Sampling rate at 50 HzSampling rate at 240 Hz

What should we keep in mind before starting. The EEG display - Montages

Recording technique: Differential Amplifiers and Polarity Conventions

Richard C. Burgess, Masaki Iwasaki, Dileep Nair. Localization and Field Determination in Electroencephalography and Magnetoencephalography. In The Treatment of Epilepsy. Editor Elaine Wyllie. Lippincot Williams&Wilkins, Fourth Edition, 2006

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Recording technique: Analogue-to-Digital conversion (ADC)

Factors that affect the accuracy of the waveform:

Sampling rate (amplifier characteristics, clinical setting ± 1KHz, research > 10 KHz)

Sampling skew Display - screen resolution (new generation 4K)

Sampling rate at 50 HzSampling rate at 240 Hz


Recording technique: Differential Amplifiers and Polarity Conventions


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A balanced compromise between physics and the user

Bipolar MontageReferential Montage

ReferencesIpsilateral earLinked earsAverageLaplacianVertexBalanced noncephalicAny other not contaminated

How to standardize the way we talk - glossary of terms

Paroxysm Graphoelement phenomenon with sudden onset, rapid attainment of a maximum, and abrupttermination; distinguished from background activity. Comment: commonly used to refer toepileptiform and seizure patterns.

Epileptiform pattern

Describes transients distinguishable from background activity with a characteristicmorphology typically, but neither exclusively nor invariably, found in interictal EEGs of peoplewith epilepsy. Epileptiform patterns have to fulfill at least 4 of the following 6 criteria:(1) Di- or tri-phasic waves with sharp or spiky morphology (i.e. pointed peak).(2) Different wave-duration than the ongoing background activity, either shorter or longer.(3) Asymmetry of the waveform: a sharply rising ascending phase and a more slowly

decaying descending phase, or vice versa.(4) The transient is followed by an associated slow after-wave.(5) The background activity surrounding epileptiform discharges is disrupted by the

presence of the epileptiform discharges.(6) Distribution of the negative and positive potentials on the scalp suggests a source of the

signal in the brain, corresponding to a radial, oblique or tangential orientation of thesource (see dipole). This is best assessed by inspecting voltage maps constructed usingcommon-average reference.

Synonyms: interictal epileptiform discharge, epileptiform activity.

A revised glossary of terms most commonly used by clinical electroencephalographers and updated proposal for the report format of theEEG findings. Revision 2017 Nick Kane, Jayant Acharya, Sandor Benickzy, Luis Caboclo, Simon Finnigan, Peter W. Kaplan, HiroshiShibasaki, Ronit Pressler, Michel J.A.M. van Putten. Clinical Neurophysiology Practice 2 (2017) 170–185

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A balanced compromise between physics and the user

Bipolar MontageReferential Montage

ReferencesIpsilateral earLinked earsAverageLaplacianVertexBalanced noncephalicAny other not contaminated


Paroxysm Graphoelement phenomenon with sudden onset, rapid attainment of a maximum, and abrupttermination; distinguished from background activity. Comment: commonly used to refer toepileptiform and seizure patterns.

Epileptiform pattern

Describes transients distinguishable from background activity with a characteristicmorphology typically, but neither exclusively nor invariably, found in interictal EEGs of peoplewith epilepsy. Epileptiform patterns have to fulfill at least 4 of the following 6 criteria:(1) Di- or tri-phasic waves with sharp or spiky morphology (i.e. pointed peak).(2) Different wave-duration than the ongoing background activity, either shorter or longer.(3) Asymmetry of the waveform: a sharply rising ascending phase and a more slowly

decaying descending phase, or vice versa.(4) The transient is followed by an associated slow after-wave.(5) The background activity surrounding epileptiform discharges is disrupted by the

presence of the epileptiform discharges.(6) Distribution of the negative and positive potentials on the scalp suggests a source of the

signal in the brain, corresponding to a radial, oblique or tangential orientation of thesource (see dipole). This is best assessed by inspecting voltage maps constructed usingcommon-average reference.

Synonyms: interictal epileptiform discharge, epileptiform activity.


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Spike A transient, clearly distinguished from background activity, with pointed peak at aconventional time scale and duration from 20 to less than 70 ms. Amplitude varies buttypically >50 µV. Main component is generally negative relative to other areas.

Comments:(1) term should be restricted to epileptiform discharges. EEG spikes should be differentiated

from sharp waves, i.e. transients having similar characteristics but longer durations.However, it should be kept in mind that this distinction is largely arbitrary and primarilyserves descriptive purposes.

(2) EEG spikes should be clearly distinguished from the brief unit spikes recorded fromsingle cells with microelectrode techniques.



Sharp wave An epileptiform transient clearly distinguished from the background activity, althoughamplitude varies. A pointed peak at a conventional time scale and duration of 70–200 ms,usually with a steeper ascending phase when compared to the descending phase. Maincomponent is generally negative relative to other areas, and may be followed by slow waveof the same polarity.

Comments:

(1) Term should be restricted to epileptiform discharges, and does not apply to:(a) Distinctive physiological events such as vertex sharp transients, lambda waves

and positive occipital sharp transients of sleep,(b) Sharp transients poorly distinguished from background activity (without or with a

slow wave for example six Hz spike-and-slow-wave).

(2) Sharp waves should be differentiated from spikes, i.e. transients having similarcharacteristics but shorter duration. However, it should be kept in mind that thisdistinction is largely arbitrary and primarily serves descriptive purposes.


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Spike A transient, clearly distinguished from background activity, with pointed peak at aconventional time scale and duration from 20 to less than 70 ms. Amplitude varies buttypically >50 µV. Main component is generally negative relative to other areas.

Comments:(1) term should be restricted to epileptiform discharges. EEG spikes should be differentiated

from sharp waves, i.e. transients having similar characteristics but longer durations.However, it should be kept in mind that this distinction is largely arbitrary and primarilyserves descriptive purposes.

(2) EEG spikes should be clearly distinguished from the brief unit spikes recorded fromsingle cells with microelectrode techniques.



Sharp wave An epileptiform transient clearly distinguished from the background activity, althoughamplitude varies. A pointed peak at a conventional time scale and duration of 70–200 ms,usually with a steeper ascending phase when compared to the descending phase. Maincomponent is generally negative relative to other areas, and may be followed by slow waveof the same polarity.

Comments:

(1) Term should be restricted to epileptiform discharges, and does not apply to:(a) Distinctive physiological events such as vertex sharp transients, lambda waves

and positive occipital sharp transients of sleep,(b) Sharp transients poorly distinguished from background activity (without or with a

slow wave for example six Hz spike-and-slow-wave).

(2) Sharp waves should be differentiated from spikes, i.e. transients having similarcharacteristics but shorter duration. However, it should be kept in mind that thisdistinction is largely arbitrary and primarily serves descriptive purposes.


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Epileptiforminterictal activity

SpikeSpike-and-slow-waveRuns of rapid spikesPolyspikesPolyspike-and-slow-waveSharp-waveSharp-and-slow-waveSlow sharp-waveHigh frequency oscillation (HFO)Hypsarrhythmia - classicHypsarrhythmia - modified

Standardized computer-based organized reporting of EEG: SCORE - Second version. Beniczky S, Aurlien H, Brøgger JC, Hirsch LJ, Schomer DL, Trinka E, Pressler RM, Wennberg R, Visser GH, Eisermann M, Diehl B, Lesser RP, Kaplan PW, Nguyen The Tich S, Lee JW, Martins-da-Silva A, Stefan H, Neufeld M, Rubboli G, Fabricius M, Gardella E, Terney D, Meritam P, Eichele T, Asano E, Cox F, van EmdeBoas W, Mameniskiene R, Marusic P, Zárubová J, Schmitt FC, Rosén I, Fuglsang-Frederiksen A, Ikeda A, MacDonald DB, Terada K, Ugawa Y, Zhou D, Herman ST. Clin Neurophysiol. 2017 Nov;128(11):2334-2346. doi: 10.1016/j.clinph.2017.07.418. Epub 2017 Aug 9. Review.

Jyoti Pillai, Michael R. Sperling. Interictal EEG and the Diagnosis of Epilepsy. Epilepsi, 47(Suppl. 1):14-22, 2006

Outline:

1. What sometimes could be confused with epileptiform activitya) Normal patternsb) Variants, not necessarily pathological

2. Misleading generalized patterns

a) During hyperventilationb) During sleep

1. State transitions2. Arousals

3. Misleading focal or regional patterns

a) Occipitalb) Temporal c) Frontald) Central

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Epileptiforminterictal activity

SpikeSpike-and-slow-waveRuns of rapid spikesPolyspikesPolyspike-and-slow-waveSharp-waveSharp-and-slow-waveSlow sharp-waveHigh frequency oscillation (HFO)Hypsarrhythmia - classicHypsarrhythmia - modified

Standardized computer-based organized reporting of EEG: SCORE - Second version. Beniczky S, Aurlien H, Brøgger JC, Hirsch LJ, Schomer DL, Trinka E, Pressler RM, Wennberg R, Visser GH, Eisermann M, Diehl B, Lesser RP, Kaplan PW, Nguyen The Tich S, Lee JW, Martins-da-Silva A, Stefan H, Neufeld M, Rubboli G, Fabricius M, Gardella E, Terney D, Meritam P, Eichele T, Asano E, Cox F, van EmdeBoas W, Mameniskiene R, Marusic P, Zárubová J, Schmitt FC, Rosén I, Fuglsang-Frederiksen A, Ikeda A, MacDonald DB, Terada K, Ugawa Y, Zhou D, Herman ST. Clin Neurophysiol. 2017 Nov;128(11):2334-2346. doi: 10.1016/j.clinph.2017.07.418. Epub 2017 Aug 9. Review.


Outline:

1. What sometimes could be confused with epileptiform activitya) Normal patternsb) Variants, not necessarily pathological

2. Misleading generalized patterns

a) During hyperventilationb) During sleep

1. State transitions2. Arousals

3. Misleading focal or regional patterns

a) Occipitalb) Temporal c) Frontald) Central

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Misleading Generalized Patterns

Diffuse slowing by hyperventilation

Hypnagogic (and also hypnopompic)hypersynchrony

Arousalspatterns

Rudimentary spike wave complex

Six Hz spike and slow wave

Recorded in 70% of normal children (3-5 years) and less then 20% of adults.The degree and abruptness of the response seem to relate directly to age. The most pronounced response occur between 8-12 years

It may be seen in normal children up to age 12-13 years, but is increasingly rare after 11 years (<10%).Burst of high amplitude, frontally predominant at 4-5 Hz, slowing to 3 Hz within the first seconds.

An abrupt shift of EEG frequency including alpha,theta, and/or frequencies greater than 16 Hz (but not spindles) that lasts 3 s, with at least 10 s of stable sleep preceding.

Generalized or nearly generalized high voltage 3-4 Hz waves with poorly developed spike in the positive trough between the slow waves. Only in drowsiness.

Also called “phantom spike and wave”, consists of brief bursts of spike-and-wave discharges at 6Hz (5-7Hz), lasting 1-2 s. At times the spike component may be difficult to see.

Only spike-slow waveor sharp-slow wave complexes or clear focal or lateralized changes can be considered abnormal.It was one of the most cause of error.

Normal state transition, may be mistaken for pathological slow or epileptiform activity.

These complex morphology patterns may be mistaken for epileptiform activity.

It is found only on infancy and early childhood.

Should be distinguished from “fragments” of more significant spike-wave complexes. 6 Hz spike-and-slow wave tend to disappearduring sleep.

Misleading focal or regional patterns: Occipital

Alpha rhythm POSTS Posterior slow waves of youth

Lambda waves

Photic drivingand visual evoked potentials

Spikes in theblind person

Normalfluctuations, alpha squeak, and paradoxical responses.

Sharp transient,positive relative to other areas. May be single or repetitive. Amplitude varies, but is generally < 50µV

Maximally expressed between 8-14 years. 15%incidence between 16-20 years

Diphasic sharp transient of waking subjects during visual exploration. The main component is positive relative to other areas.

Physiologicresponse of rhythmic activity elicited by repetitive photic stimulation at frequencies 5-30 Hz

Needle-like spikes that develop in most congenitally blind children. Completely disappearduring childhood or adolescence.

Alpha variants (sub-harmonics). Notched appearance.Sharp alpha.

Fused waves intermixed with alpha

Time locked to saccadic eye movements. Amplitude varies, but is generally < 50µV. In a routine EEG may be quite asymmetrical.

VEP elicited by isolated flashes or repeated at very low frequency

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Misleading Generalized Patterns

Diffuse slowing by hyperventilation

Hypnagogic (and also hypnopompic)hypersynchrony

Arousalspatterns

Rudimentary spike wave complex

Six Hz spike and slow wave

Recorded in 70% of normal children (3-5 years) and less then 20% of adults.The degree and abruptness of the response seem to relate directly to age. The most pronounced response occur between 8-12 years

It may be seen in normal children up to age 12-13 years, but is increasingly rare after 11 years (<10%).Burst of high amplitude, frontally predominant at 4-5 Hz, slowing to 3 Hz within the first seconds.

An abrupt shift of EEG frequency including alpha,theta, and/or frequencies greater than 16 Hz (but not spindles) that lasts 3 s, with at least 10 s of stable sleep preceding.

Generalized or nearly generalized high voltage 3-4 Hz waves with poorly developed spike in the positive trough between the slow waves. Only in drowsiness.

Also called “phantom spike and wave”, consists of brief bursts of spike-and-wave discharges at 6Hz (5-7Hz), lasting 1-2 s. At times the spike component may be difficult to see.

Only spike-slow waveor sharp-slow wave complexes or clear focal or lateralized changes can be considered abnormal.It was one of the most cause of error.

Normal state transition, may be mistaken for pathological slow or epileptiform activity.

These complex morphology patterns may be mistaken for epileptiform activity.

It is found only on infancy and early childhood.

Should be distinguished from “fragments” of more significant spike-wave complexes. 6 Hz spike-and-slow wave tend to disappearduring sleep.

Misleading focal or regional patterns: Occipital

Alpha rhythm POSTS Posterior slow waves of youth

Lambda waves

Photic drivingand visual evoked potentials

Spikes in theblind person

Normalfluctuations, alpha squeak, and paradoxical responses.

Sharp transient,positive relative to other areas. May be single or repetitive. Amplitude varies, but is generally < 50µV

Maximally expressed between 8-14 years. 15%incidence between 16-20 years

Diphasic sharp transient of waking subjects during visual exploration. The main component is positive relative to other areas.

Physiologicresponse of rhythmic activity elicited by repetitive photic stimulation at frequencies 5-30 Hz

Needle-like spikes that develop in most congenitally blind children. Completely disappearduring childhood or adolescence.

Alpha variants (sub-harmonics). Notched appearance.Sharp alpha.

Fused waves intermixed with alpha

Time locked to saccadic eye movements. Amplitude varies, but is generally < 50µV. In a routine EEG may be quite asymmetrical.

VEP elicited by isolated flashes or repeated at very low frequency

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Misleading focal or regional patterns: Temporal

Slowing in elderly subjects

Wicket spikes BETS (benignepileptiform transients of sleep)

RTTD (rhythmic temporal theta of drowsiness)

14 and 6 Hz positive burst

SREDA (subclinical rhythmicelectrographic discharge in adults)

20% between 40-59 years40% between 60-79 years> 30% after 60 years old had focal delta activity

Spike-like monophasicsingle waves or trains of waves, arciform or mu-like, 6-11 Hz, amplitude ranging from 60 to 200 µV,

small sharp spikes of very short duration (<50 mseg) and low amplitude (<50µV), often followed by a small theta wave.

Burst of 4-7 Hz waves frequentlynotched by faster waves, during drowsiness

Burst of arch-shaped waves at 13-17 and/or 5-7 Hz (frequently 14 and/or 6 Hz) posterior temporal (and adjacent) on one or both sides.

Maximal amplitude over parietal-posterior temporal, sharp contoured theta (occasionallydelta), theaverage duration is 40-80 sec.

Left > right sideFused morphology

Mainly in adults during drowsiness, on one or both sides

Occurs during drowsiness and light sleep, on one or both sides, often asynchronously

May occur bilaterally or independentlyover the two hemispheres, or shifting. Begin and end gradually

Amplitude generally below 75µV. The sharp peaks are positive

It may resemble a seizure discharge but is not accompanied by any clinical manifestations.

Misleading focal or regional patterns: Frontal

Eye movements and muscle artifacts

K complex Photomyogenicresponse

FAR (frontal arousal rhythm)

Effect of low frequency filters on eye movements and on muscle artifact.Eye flutterLateral rectus spikes

Amplitude is generally maximal in the frontal vertex. Duration > 0,5 sec.Mitten pattern. The sharp component (the thumb) precedes the slow wave (the hand), with a similar appearance of a sharp and slow wave complex.

A response to IPS characterized by the appearance of brief repetitive muscular artifacts (spikes), often increase gradually in amplitude as stimuli are continued and cease promptly

Prolonged (up to 20 sec) rhythmical sharp and spiky activity, 7 to 10 Hz, over the frontal areas (maximum frontal midline)

A burst of a high voltage negative slow wave followed by a smaller positive slow wave frequently associated with a sleep spindle

Frequently associated with flutter of the eyelids,vertical oscillations of the eyeballs and discrete jerking musculature of the face and head.

Seen at arousal from sleep mainly in children with minimal cerebral dysfunction. It is considered a nonspecific pattern.

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Misleading focal or regional patterns: Temporal

Slowing in elderly subjects

Wicket spikes BETS (benignepileptiform transients of sleep)

RTTD (rhythmic temporal theta of drowsiness)

14 and 6 Hz positive burst

SREDA (subclinical rhythmicelectrographic discharge in adults)

20% between 40-59 years40% between 60-79 years> 30% after 60 years old had focal delta activity

Spike-like monophasicsingle waves or trains of waves, arciform or mu-like, 6-11 Hz, amplitude ranging from 60 to 200 µV,

small sharp spikes of very short duration (<50 mseg) and low amplitude (<50µV), often followed by a small theta wave.

Burst of 4-7 Hz waves frequentlynotched by faster waves, during drowsiness

Burst of arch-shaped waves at 13-17 and/or 5-7 Hz (frequently 14 and/or 6 Hz) posterior temporal (and adjacent) on one or both sides.

Maximal amplitude over parietal-posterior temporal, sharp contoured theta (occasionallydelta), theaverage duration is 40-80 sec.

Left > right sideFused morphology

Mainly in adults during drowsiness, on one or both sides

Occurs during drowsiness and light sleep, on one or both sides, often asynchronously

May occur bilaterally or independentlyover the two hemispheres, or shifting. Begin and end gradually

Amplitude generally below 75µV. The sharp peaks are positive

It may resemble a seizure discharge but is not accompanied by any clinical manifestations.

Misleading focal or regional patterns: Frontal

Eye movements and muscle artifacts

K complex Photomyogenicresponse

FAR (frontal arousal rhythm)

Effect of low frequency filters on eye movements and on muscle artifact.Eye flutterLateral rectus spikes

Amplitude is generally maximal in the frontal vertex. Duration > 0,5 sec.Mitten pattern. The sharp component (the thumb) precedes the slow wave (the hand), with a similar appearance of a sharp and slow wave complex.

A response to IPS characterized by the appearance of brief repetitive muscular artifacts (spikes), often increase gradually in amplitude as stimuli are continued and cease promptly

Prolonged (up to 20 sec) rhythmical sharp and spiky activity, 7 to 10 Hz, over the frontal areas (maximum frontal midline)

A burst of a high voltage negative slow wave followed by a smaller positive slow wave frequently associated with a sleep spindle

Frequently associated with flutter of the eyelids,vertical oscillations of the eyeballs and discrete jerking musculature of the face and head.

Seen at arousal from sleep mainly in children with minimal cerebral dysfunction. It is considered a nonspecific pattern.

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Misleading focal or regional patterns: central (vertex)

Vertex sharp transient (V wave)

Sleep spindles Saw toothed waves Midline theta rhythm (Cigánek)

Sharp potential,maximal at the vertex, negative relative to other areas, occurring in sleep. May be single or repetitive. Amplitude varies but rarely exceeds 250 µV.

Burst at 11-15 Hz but mostly at 12-14 Hz generally diffuse but of higher voltage over the central regions, occurring during sleep. Amplitude varies but is mostly < 50µV in adults.

Vertex negative 2-5 Hz waves occurring in trains during REM sleep.

It consists of a rhythmic train of activity at 5-7 Hz, may have a smooth, sinusoidal, arciform, spiky or mu-like appearance. Tens to wax and wane. It is present during wakefulness and drowsiness

V waves often differ in appearance from one wave to the next. In children may be spike-like.

Cases of extreme sleep spindles and spindlesasymmetry

In a routine EEG is just occasionally seen and may be misinterpreted.

Although described in epileptic patients it appears to represent a nonspecific variant of theta activity.

Misleading focal or regional patterns: Any location

Breach rhythm

EEG activity recorded over or nearby a defect in the skull vault (for example after a fracture, burr hole or craniotomy), of increased amplitude when compared to homologous areas on the opposite side of the head (usually by a factor of less than 3). The rhythm is composed of fast activity with a spiky appearance along with alpha and/or mu rhythms, due to lack of attenuation and distortion by the skull, usually in the 6-11 Hz range, does not respond to movements.

A physiological variant to be distinguished from epileptiform activity, although it may be associated with underlying brain injury and therefore a liability to focal seizures.

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Misleading focal or regional patterns: central (vertex)

Vertex sharp transient (V wave)

Sleep spindles Saw toothed waves Midline theta rhythm (Cigánek)

Sharp potential,maximal at the vertex, negative relative to other areas, occurring in sleep. May be single or repetitive. Amplitude varies but rarely exceeds 250 µV.

Burst at 11-15 Hz but mostly at 12-14 Hz generally diffuse but of higher voltage over the central regions, occurring during sleep. Amplitude varies but is mostly < 50µV in adults.

Vertex negative 2-5 Hz waves occurring in trains during REM sleep.

It consists of a rhythmic train of activity at 5-7 Hz, may have a smooth, sinusoidal, arciform, spiky or mu-like appearance. Tens to wax and wane. It is present during wakefulness and drowsiness

V waves often differ in appearance from one wave to the next. In children may be spike-like.

Cases of extreme sleep spindles and spindlesasymmetry

In a routine EEG is just occasionally seen and may be misinterpreted.

Although described in epileptic patients it appears to represent a nonspecific variant of theta activity.

Misleading focal or regional patterns: Any location

Breach rhythm

EEG activity recorded over or nearby a defect in the skull vault (for example after a fracture, burr hole or craniotomy), of increased amplitude when compared to homologous areas on the opposite side of the head (usually by a factor of less than 3). The rhythm is composed of fast activity with a spiky appearance along with alpha and/or mu rhythms, due to lack of attenuation and distortion by the skull, usually in the 6-11 Hz range, does not respond to movements.

A physiological variant to be distinguished from epileptiform activity, although it may be associated with underlying brain injury and therefore a liability to focal seizures.

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Take-home message

For an epileptologist or a clinical neurophysiologist the expression “do not harm” means avoid “overreading”!

Avoid the “looking to hard” syndrome!

Be conservative but always meticulous.

References:Beniczky S, Aurlien H, Brøgger JC, Hirsch LJ, Schomer DL, Trinka E, Pressler RM, Wennberg R, Visser GH, Eisermann M, Diehl B, Lesser RP, Kaplan PW, Nguyen The Tich S, Lee JW, Martins-da-Silva A, Stefan H, Neufeld M, Rubboli G, Fabricius M, Gardella E, Terney D, Meritam P, Eichele T, Asano E, Cox F, van Emde Boas W, Mameniskiene R, Marusic P, Zárubová J, Schmitt FC, Rosén I, Fuglsang-Frederiksen A, Ikeda A, MacDonald DB, Terada K, Ugawa Y, Zhou D, Herman ST. Standardized computer-based organized reporting of EEG: SCORE -Second version. Clin Neurophysiol. 2017 Nov;128(11):2334-2346. doi: 10.1016/j.clinph.2017.07.418. Epub 2017 Aug 9. Review.

Nick Kane, Jayant Acharya, Sandor Benickzy, Luis Caboclo, Simon Finnigan, Peter W. Kaplan, Hiroshi Shibasaki, Ronit Pressler, Michel J.A.M. van Putten A revised glossary of terms most commonly used by clinical electroencephalographers and updated proposal for the report format of the EEG findings. Revision 2017. Clinical Neurophysiology Practice 2 (2017) 170–185

Navarrete M, Alvarado-Rojas C, Le Van Quyen M, Valderrama M . RIPPLELAB: A Comprehensive Application for the Detection, Analysis and Classification of High Frequency Oscillations in Electroencephalographic Signals. PLoS One. 2016 Jun 24;11(6):e0158276. doi: 10.1371/journal.pone.0158276. eCollection 2016.

Beleza P, Bilgin O, Noachtar S. Interictal rhythmical midline theta differentiates frontal from temporal lobe epilepsies. Epilepsia 2009; 50: 550-555.

Erik K, Lauren C F. Electroencephalography. An Introductory Text and Atlas of Normal and Abnormal Findings in Adults, Children, and Infants. AES, 2016

Gyorgy Buzsáki. Rhythms of the brain, Oxford University Press 2006

Adrian J. Fowle, Colin D. Binnie. Uses and abuses of the EEG in Epilepsy. Epilepsia, 41 (suppl. 3):S10-S18, 2000

Barbara F. Westmoreland. Benign EEG variants and Patterns of Uncertain Clinical Significance. In Current Practice of ClinicalElectroencephalography, Second Edition, edited by D. D. Daly and T. A. Pedley, Raven Press, 1990


Tatum WO 4th, Husain AM, Benbadis SR, Kaplan PW. Normal adult EEG and patterns of uncertain significance. J Clin Neurophysiol. 2006 Jun;23(3):194-207.

Richard L. Cervone, Adrew S. Blum. Normal Variant EEG Patterns. In The Clinical Neurophysiology Pimer. Edited by: A. S. Blum and S. B. Rutkove. Humana Press, 2007

Soheyl Noachtar, Elaine Wyllie. Electroencephalographic Atlas of Epileptiform Abormalities. In The Treatment of Epilepsy. Editor Elaine Wyllie. Lippincot Williams&Wilkins, Fourth Edition, 2006

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Take-home message

For an epileptologist or a clinical neurophysiologist the expression “do not harm” means avoid “overreading”!

Avoid the “looking to hard” syndrome!

Be conservative but always meticulous.

References:Beniczky S, Aurlien H, Brøgger JC, Hirsch LJ, Schomer DL, Trinka E, Pressler RM, Wennberg R, Visser GH, Eisermann M, Diehl B, Lesser RP, Kaplan PW, Nguyen The Tich S, Lee JW, Martins-da-Silva A, Stefan H, Neufeld M, Rubboli G, Fabricius M, Gardella E, Terney D, Meritam P, Eichele T, Asano E, Cox F, van Emde Boas W, Mameniskiene R, Marusic P, Zárubová J, Schmitt FC, Rosén I, Fuglsang-Frederiksen A, Ikeda A, MacDonald DB, Terada K, Ugawa Y, Zhou D, Herman ST. Standardized computer-based organized reporting of EEG: SCORE -Second version. Clin Neurophysiol. 2017 Nov;128(11):2334-2346. doi: 10.1016/j.clinph.2017.07.418. Epub 2017 Aug 9. Review.

Nick Kane, Jayant Acharya, Sandor Benickzy, Luis Caboclo, Simon Finnigan, Peter W. Kaplan, Hiroshi Shibasaki, Ronit Pressler, Michel J.A.M. van Putten A revised glossary of terms most commonly used by clinical electroencephalographers and updated proposal for the report format of the EEG findings. Revision 2017. Clinical Neurophysiology Practice 2 (2017) 170–185

Navarrete M, Alvarado-Rojas C, Le Van Quyen M, Valderrama M . RIPPLELAB: A Comprehensive Application for the Detection, Analysis and Classification of High Frequency Oscillations in Electroencephalographic Signals. PLoS One. 2016 Jun 24;11(6):e0158276. doi: 10.1371/journal.pone.0158276. eCollection 2016.

Beleza P, Bilgin O, Noachtar S. Interictal rhythmical midline theta differentiates frontal from temporal lobe epilepsies. Epilepsia 2009; 50: 550-555.

Erik K, Lauren C F. Electroencephalography. An Introductory Text and Atlas of Normal and Abnormal Findings in Adults, Children, and Infants. AES, 2016

Gyorgy Buzsáki. Rhythms of the brain, Oxford University Press 2006

Adrian J. Fowle, Colin D. Binnie. Uses and abuses of the EEG in Epilepsy. Epilepsia, 41 (suppl. 3):S10-S18, 2000

Barbara F. Westmoreland. Benign EEG variants and Patterns of Uncertain Clinical Significance. In Current Practice of ClinicalElectroencephalography, Second Edition, edited by D. D. Daly and T. A. Pedley, Raven Press, 1990


Tatum WO 4th, Husain AM, Benbadis SR, Kaplan PW. Normal adult EEG and patterns of uncertain significance. J Clin Neurophysiol. 2006 Jun;23(3):194-207.

Richard L. Cervone, Adrew S. Blum. Normal Variant EEG Patterns. In The Clinical Neurophysiology Pimer. Edited by: A. S. Blum and S. B. Rutkove. Humana Press, 2007

Soheyl Noachtar, Elaine Wyllie. Electroencephalographic Atlas of Epileptiform Abormalities. In The Treatment of Epilepsy. Editor Elaine Wyllie. Lippincot Williams&Wilkins, Fourth Edition, 2006

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References:

Erwin-Josef Speckman, Christian E. Elger, Ulrich Altrup. Neurophysiologic Basis of the Electroencephalogram. In The Treatment of Epilepsy. Editor Elaine Wyllie. Lippincot Williams&Wilkins, Fourth Edition, 2006


Catarino CB, Vollmar C, Noachtar S. Paradoxical lateralization of non-invasive electroencephalographic ictal patterns in extra-temporal epilepsies. Epilepsy Res. 2012 Mar;99(1-2):147-55. doi: 10.1016/j.eplepsyres.2011.11.002. Epub 2011 Nov 30


Thank you

And enjoy the Course

[email protected]

4/9/2018

16

References:

Erwin-Josef Speckman, Christian E. Elger, Ulrich Altrup. Neurophysiologic Basis of the Electroencephalogram. In The Treatment of Epilepsy.Editor Elaine Wyllie. Lippincot Williams&Wilkins, Fourth Edition, 2006


Catarino CB, Vollmar C, Noachtar S. Paradoxical lateralization of non-invasive electroencephalographic ictal patterns in extra-temporalepilepsies. Epilepsy Res. 2012 Mar;99(1-2):147-55. doi: 10.1016/j.eplepsyres.2011.11.002. Epub 2011 Nov 30

James X. Tao, Amit Ray, Susan Hawes-Ebersole, John S. Ebersole. Intracranial EEG Substrates of Scalp EEG Interictal Spikes. Epilepsia,46(5):669–676, 2005

Thank you

And enjoy the Course

[email protected]

ean/ilae-cea: how to approach eeg and avoid overreading …4rd congress of the european academy of...

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