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ERS Annual Congress Amsterdam
26–30 September 2015
EDUCATIONAL MATERIAL
Educational Skills Workshop 25, 27
Hands-on polysomnography
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Wednesday, 30 September 2015
ESW25 08:00–10:20
ESW27 10:40–13:00
Room L001 RAI
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Educational Skills Workshop 25, 27
Hands-on polysomnography
AIMS: To introduce and provide an overview of polysomnography, including wiring up,
troubleshooting signals, scoring studies, and interpreting the report.
TARGET AUDIENCE: Absolute beginners and anyone wishing to refresh their understanding of full
polysomnographic sleep studies, including physicians, nurses, allied health professionals, students,
and researchers with a professional interest in sleep medicine.
CHAIRS: R. L. Riha (Edinburgh, United Kingdom)
FACILITATORS: S. De Lacy (London, United Kingdom), E. Hill (Edinburgh, United Kingdom),
A. Morley (Glasgow, United Kingdom)
WORKSHOP PROGRAMME
PAGE
Four 30-minute workstations run simultaneously on the following topics:
Workstation 1 – Approach to full polysomnography, setting up and wiring up:
the basic techniques
10-20 system EEG Placement
5
Workstation 2 – Data acquisition: what can go wrong? What does it look like
when it goes right?
PSG Artifact Recognition and Resolution
17
Workstation 3 – Scoring sleep using AASM guidelines. A brief introduction to scoring
respiratory events, arousals and limb movements.
73
Additional resources
132
Faculty disclosures
133
Faculty contact information
134
Answers to evaluation questions
135
ERS monograph
Obstructive Sleep Apnoea
Edited by Ferran Barbé and Jean-Louis Pépin
ISBN 978-1-84984-059-0
Comprehensive and up-to-date chapters provide the reader with a concise overview of obstructive
sleep apnoea, making this book a useful reference for pulmonologists concerned with the management
of this disease.
To buy printed copies, visit the ERS Bookshop at the ERS International Congress 2015
(Hall 1, Stand 1.D_12).
If you’re an ERS member, you automatically have full online access to the ERS Monographs.
Find out more ERSPUBLICATIONS.COM
The International 10-20 EEG system: A brief introduction
Dr Andrew Morley
Royal Hospital for Sick Children
79 Hardgate Rd
G51 4SX Glasgow
UNITED KINGDOM
[email protected]
SUMMARY
The non‐invasive method for recording electrical activity of the brain Electroencephalography
(EEG) in relation to sleep is a key element of any Polysomnography assessment. This
workstation will focus on how to set‐up an EEG sleep montage in accordance with the
American Academy of Sleep medicine.
This element of the workshop will be mainly a practical session. It will provide small group
teaching, hands‐on experience with equipment and will ensure that all participants will be fully
involved.
EVALUATION
1. Why should you perform bio‐calibrations before the start of a polysomnography sleep
study?
a. To check the reliability of signals.
b. Confirm the polarity of signals.
c. Establish a baseline reference for the study.
d. All of the above.
2. An eye movement to the left should result in ______ when using standard convention
for polarity.
a. An upward deflection of the signals for both channels
b. An upward deflection of the signal for the LOC channel and a downward deflection
on the ROC channel
c. A downward deflection of the signal for LOC channel and an upward deflection on
the ROC channel.
d. A downward deflection of the signal for both channels.
3. The total circumference of the head is 48cm. What is the distance from Oz to O2
a. 24cm
b. 9.6cm
c. 2.4cm
d. 4.8cm
4. Which electrode site is found half way between M1 & M2
a. Fz
b. Cz
c. Oz
d. Fpz
5. For EEG electrodes what is the recommended level for impedance?
a. < 1K Ohms
b. <5 k Ohms
c. < 10k Ohms
d. ≤ 10 k Ohms
5
Slide 1
___________________________________
___________________________________
10-20 system EEG Placement
Andrew Morley
(BSc Hons, RPSGT)
Chief Respiratory (Sleep) Physiologist, Royal Hospital for Sick Children, Glasgow
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 2
Conflict of interest disclosure
x I have no, real or perceived, direct or indirect conflicts of interest that relate to this

presentation.
 I have the following, real or perceived direct or indirect conflicts of interest that relate to
this presentation:
Affiliation / financial interest
___________________________________
___________________________________
Nature of conflict / commercial company name
Tobacco-industry and tobacco corporate affiliate
related conflict of interest
Grants/research support (to myself, my institution or
department):
___________________________________
Honoraria or consultation fees:
Participation in a company sponsored bureau:
___________________________________
Stock shareholder:
Spouse/partner:
Other support or other potential conflict of interest:
This event is accredited for CME credits by EBAP and speakers are required to disclose their potential conflict of
interest going back 3 years prior to this presentation. The intent of this disclosure is not to prevent a speaker with a
conflict of interest (any significant financial relationship a speaker has with manufacturers or providers of any
commercial products or services relevant to the talk) from making a presentation, but rather to provide listeners with
information on which they can make their own judgment. It remains for audience members to determine whether the
speaker’s interests or relationships may influence the presentation.
Drug or device advertisement is strictly forbidden.
___________________________________
___________________________________
___________________________________
___________________________________
Slide 3
10-20 EEG Placement
AIMS
• Demonstrate the International 10‐20 EEG system
• Understand steps required to set‐up a10‐20 EEG montage for a Polysomnography sleep study. • Give each delegate a practical experience setting up a Sleep EEG montage using the 10‐20 EEG system.
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
6
Slide 4
___________________________________
10-20 EEG Placement
Workshop Plan
• This session is going to be a mainly practical session.
___________________________________
___________________________________
• Brief presentation : 10‐20 basics
• Split into pairs and have a go.
• Slides from the session are available as part of the workshop materials – via website
___________________________________
___________________________________
___________________________________
___________________________________
Slide 5
___________________________________
10-20 EEG Placement
Focus
• Head measuring ___________________________________
___________________________________
• Location of EEG, EOG, EMG • Skin preparation / application (incl. differing techniques)
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 6
10-20 EEG Placement
What is the 10-20 system?
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
7
Slide 7
___________________________________
10-20 EEG Placement
___________________________________
What is the 10-20 system?
• An internationally recognised method that allows EEG electrode placement to be standardised.
• Ensures inter‐electrode spacing is equal ___________________________________
•Electrode placements proportional to skull size & shape ___________________________________
• Covers all brain regions F = Frontal P = Parietal T = Temporal O = Occipital ___________________________________
• Numbering system Odd = left side,
Even = right side,
___________________________________
Z = midline ___________________________________
Slide 8
___________________________________
10-20 EEG Placement
___________________________________
Routine EEG Montage
___________________________________
• 16 Channel ( + references e.g. Cz, Ground)
M
M11
M1
M2
M2
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 9
10-20 EEG Placement
American Academy of Sleep Medicine
• Utilises 10‐20 for polysomnography studies
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
8
Slide 10
___________________________________
10-20 EEG Placement
Sleep Montage
___________________________________
Sleep PSG montage (8 Channels + References & ground)
___________________________________
Recommended
• F3‐M2 • C3‐M2 • O1‐M2
___________________________________
Back‐up
• F4‐M1
• C4‐M2 • O2‐M1 (There are other acceptable derivations.)
___________________________________
“A minimum of 3 EEG derivations are required in order to sample activity from the frontal central and occipital regions”
___________________________________
The AASM Manual for the Scoring of Sleep and Associated Events. Version 2.0
___________________________________
Slide 11
___________________________________
10-20 EEG Placement
Why a minimum of 3 EEG derivations?
F4‐M1 – best for slow waves
___________________________________
___________________________________
___________________________________
C4‐M1 – best for spindles
___________________________________
O2‐M1 – best for alpha rhythm
___________________________________
___________________________________
___________________________________
Slide 12
10-20 EEG Placement
Preparation
___________________________________
___________________________________
___________________________________
Be prepared
___________________________________
___________________________________
___________________________________
9
Slide 13
___________________________________
10-20 EEG Placement
___________________________________
Preparation
You will need:
• Measuring tape
• Wax pencil
• Measurement ‘cheat sheet’
• Alcohol wipes
• Scarify skin – Stick / blunt needle
• Abrasive paste
• Conductive paste/gel
• Collodion glue
• Razor?
___________________________________
___________________________________
Measurement
30.0
31.0
32.0
33.0
34.0
35.0
36.0
37.0
10%
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
20%
6.0
6.2
6.4
6.6
6.8
7.0
7.2
7.4
___________________________________
___________________________________
___________________________________
Slide 14
___________________________________
10-20 EEG Placement
Skin Preparation
How ?
• Isopropyl alcohol wipes to clean (removes grease) • Abrasive paste & cotton tip to reduce skin impedance (removes dead skin cells)
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 15
10-20 EEG Placement
Why is it important
___________________________________
Need to have good electrical contact
Impedance < 5kOhms
___________________________________
Consequences of poor placement
• ECG artifact
• Movement artifact
• High impedance
• Electrode popping
• Movement artifact
• Sweat sway
___________________________________
High impedance
___________________________________
___________________________________
___________________________________
10
Slide 16
___________________________________
10-20 EEG Placement
___________________________________
Why bother?
“Garbage In, Garbage Out”
___________________________________
Computers will unquestioningly process the most
nonsensical of input data (garbage in) and produce
nonsensical output (garbage out).
___________________________________
___________________________________
Sleep study signal pathway
Patient
Headbox
Sensor
Amplifier
Computer
___________________________________
___________________________________
Slide 17
___________________________________
10-20 EEG Placement
___________________________________
What is the 10-20 system?
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 18
10-20 EEG Placement
___________________________________
Four Skull Landmarks
• Nasion
• Inion
___________________________________
Nasion
• Left Pre‐auricular point
• Right Pre‐auricular point
___________________________________
Inion
Pre-auricular point
( Left & right)
___________________________________
___________________________________
___________________________________
11
Slide 19
___________________________________
10-20 EEG Placement
___________________________________
Measurement of Cz
___________________________________
• Measure the distance from pre‐auricular point to pre‐
auricular point • Mark the midpoint (50%) with a vertical line • This cross represents Cz which has been correctly aligned in the horizontal & vertical planes M
M
___________________________________
___________________________________
___________________________________
___________________________________
Slide 20
___________________________________
10-20 EEG Placement
___________________________________
Measurements - T3, C3, Cz, C4, T4
• Reapply the tape transversally between the pre‐auricular points • The midpoint (50%) should cross with previous point marking for Cz, confirming its location.
___________________________________
• Mark 10%, 20%, 20%, 20%, 20%, 10% = T3,C3, Cz, C4, T4 ___________________________________
M
M
___________________________________
___________________________________
___________________________________
___________________________________
Slide 21
10-20 EEG Placement
___________________________________
Measurements - Fpz, Fz, Cz, Pz, Oz
___________________________________
• Reapply the tape along the midline from nasion to inion • Mark 10%, 20%, 20%, 20%, 20%, 10% = Fpz, Fz, Cz, Pz, Oz M
M
___________________________________
___________________________________
___________________________________
___________________________________
12
Slide 22
___________________________________
10-20 EEG Placement
Measurements - Fp1, F7, T3, T5, O1, Oz
• Measure the distance between Fpz & Oz by applying the tape around the head via T3. • Mark at 10%, 20%, 20%, 20%, 20%, 10% = Fp1, F7, T3, T5, O1, Oz
___________________________________
___________________________________
___________________________________
___________________________________
(Repeat the process using T4 to mark O2)
___________________________________
___________________________________
Slide 23
___________________________________
10-20 EEG Placement
Measurement - F3
• Measure Fp1 to C3 and mark midpoint
___________________________________
___________________________________
• Measure Fz to F7 and mark midpoint ___________________________________
• Mark 50% = F3
(Repeat the process using Fp2 to C4 & Fz to F8 to mark F4)
___________________________________
___________________________________
___________________________________
___________________________________
Slide 24
10-20 EEG Placement
Measurements M1 & M2
• M1 & M2 are the reference electrodes (formally known as A1 & A2) • M1 & M2 are placed on the mastoid (M) process. • These are the bony prominences behind the ears. ___________________________________
___________________________________
___________________________________
___________________________________
M2
___________________________________
___________________________________
13
Slide 25
___________________________________
10-20 EEG Placement
___________________________________
C3
F3
O1
M1
You have now completed a 10‐20 EEG montage !!
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 26
___________________________________
10-20 EEG Placement
Electro-oculogram
• Recording of the movement of the corneo‐retinal potential difference,
not the movement of eye muscle.
___________________________________
___________________________________
• Electrodes are placed at outer canthus of eyes offset 1cm above/below the horizontal
• Right out and up / Left out and down
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 27
10-20 EEG Placement
Electromyogram (Chin EMG)
___________________________________
___________________________________
• 3 electrodes • 1 on mentalis • 2 on submentalis – 2 cm apart (1cm in Paediatrics) 1 Mentalis
2 Submentalis
___________________________________
___________________________________
___________________________________
___________________________________
14
Slide 28
___________________________________
10-20 EEG Placement
___________________________________
___________________________________
M1
M2
___________________________________
___________________________________
You have now completed the EOG & EMG elements of a sleep montage setup !!
___________________________________
___________________________________
Slide 29
___________________________________
10-20 EEG Placement
Calibration (Checking the signals)
___________________________________
• Eyes closed for 30 seconds
Ask the patient to close his/her eyes & lie quietly.
• Eyes open for 30 seconds
Ask the patient to open his/her eyes & look straight ahead.
___________________________________
• Look right & left
Ask the patient without their head to look to the right then to the left several times.
• Look up & down
Ask the patient without moving their head to look up then down several times.
• Blink eyes
___________________________________
Ask the patient to blink their eyes 5 times.
• Clench jaw
Ask the patient clench their jaw.
• Flex foot
Ask the patient to point & flex their foot. Repeat for other foot. Repeat for each leg and document on study.
___________________________________
• Breathe in & out
Ask the patient to breathe normally, and then take a breath in and out. Check polarity and mark IN & OUT on study.
• Snore sound
Ask the patient to imitate a snore sound.
___________________________________
___________________________________
___________________________________
Slide 30
10-20 EEG Placement
Practical Session
Your turn !!!
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
15
Slide 31
Further Reading
The AASM annual for the Scoring of Sleep and Associated Events: Rules, Terminology and technical Specifications. Version 2.1
American Academy of Sleep Medicine (2014)
Sleep Medicine Textbook (European Sleep Research Society (ESRS)
Claudio Bassetti, Zoran Dogas, Philippe Peigneux, Regensburg, (2014)
Essentials of Polysomnography.
William H. Spriggs; Jones & Bartlett Publishers (2008)
___________________________________
___________________________________
___________________________________
Essentials of Sleep Technology
Richard S. Rosenberg; American Academy of Sleep Medicine (2010)
Atlas of Clinical Polysomnography Second Edition (Two-volume Set)
Nic Butkov Media matrix , (2011)
The ten twenty system of the International Federation. Electroencephalography and Clinical
Jasper, H.H. , Neurophysiology, 1958, 10:371-375.
Polysomnographic technique: An overview. In: Sleep disorders medicine, 2nd ed. Boston
Chokroverty S. Butterworth Heinemann (1999)
Fundamentals of EEG technology, Volume 1: Basic concepts and methods.
Tyner F, Knott J, Mayer W Jr. New York: Raven Press; (1983).
Sleep medicine.
Lee-Chiong T, Sateia M, Carskadon M, (Hanley & Belfus, 2002)
___________________________________
___________________________________
___________________________________
___________________________________
Slide 32
Further Training
•
Practical Polysomnography – Edinburgh, UK
– Various dates
•
Edinburgh Sleep Medicine Course – Edinburgh, UK
– March 2016
•
European Sleep School – Orihuela Costa, Spain
– Various dates
•
International Sleep Medicine Course – Cardiff, UK
– June 2016
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Slide 33
Any Questions?
___________________________________
___________________________________
___________________________________
[email protected]
___________________________________
___________________________________
___________________________________
___________________________________
16
PSG Artifact Recognition and Resolution
Prof. Dr Simone De Lacy
European Sleep School
Orihuela Costa
SPAIN
[email protected]
SUMMARY
Recording physiological signals using surface electrodes and sensors invariably includes picking up
extraneous signals from other sources, be they externally or internally generated. Recognition of these
‘unwanted’ intrusions to desired physiological signals is an important part of the PSG analysis.
Some of these artifact can be addressed and resolved, using various techniques and software
capabilities. Others are indeed evidence of sleep or physiological pathologies and should be identified
and reported.
EVALUATION
1. The major determinant of signal impedance is:
a. The length of the electrode lead
b. The preparation of the stratum corneum
c. The thickness of the skull
d. The material used on the electrode surface
2. A low frequency filter set at 0.3 Hz will do all of the following except:
a. Reduce the amplitude of delta activity
b. Leave faster frequencies intact
c. Reduce the amplitude of sleep spindles
d. Reduce respiratory artifact
3. A ‘Low Pass’ filter set at 35 Hz will do all of the following except:
a. Increase the amplitude of sleep spindles
b. Reduce muscle artefact
c. Leave alpha, delta and theta frequencies intact
d. Reduce external electrical artifact
4.
Which of the following is an example of physiological artifact on an EEG channel:
a. ECG signal on C4:M1
b. Electrode ‘popping’
c. 50 Hz frequencies
d. 0.1 Hz frequencies
5. All of the following might be used to reduce signal artifact except:
a. Cleaning and scarification of the skin
b. Notch filters
c. Cooling the patient by lowering the ambient temperature
d. Waking the patient to remove and replace a dislodged mastoid electrode
17
PSG: Artifact Recognition and Resolution
Simone de Lacy
BSc RPSGT EST
Director, European Sleep School, Spain
18
Conflict of interest disclosure
I have no, real or perceived, direct or indirect conflicts of interest that relate to this
presentation.
Affiliation / financial interest
Nature of conflict / commercial company name
Tobacco-industry and tobacco corporate affiliate related
conflict of interest
None
Grants/research support (to myself, my institution or
department):
None
Honoraria or consultation fees:
None
Participation in a company sponsored bureau:
None
Stock shareholder:
None
Spouse/partner:
None
Other support or other potential conflict of interest:
None
This event is accredited for CME credits by EBAP and speakers are required to disclose their potential conflict of interest going
back 3 years prior to this presentation. The intent of this disclosure is not to prevent a speaker with a conflict of interest (any
significant financial relationship a speaker has with manufacturers or providers of any commercial products or services relevant to
the talk) from making a presentation, but rather to provide listeners with information on which they can make their own judgment.
It remains for audience members to determine whether the speaker’s interests or relationships may influence the presentation.
Drug or device advertisement is strictly forbidden.
19
AIMS
• To recognise common artefact in PSG recordings
• To determine if the artefact is physiological or extraneous
• To learn how to minimise, resolve or report it.
20
SIGNAL ARTIFACT
• Signal artifact refers to extraneous signals appearing within desired or
pure signal waveforms
• Some artifact is extrinsic: environmental or equipment related
• Some artifact is intrinsic (i.e. generated within the body;
physiological/ Pathological)
• Artifact needs to be recognised and resolved
4
21
INTRINSIC AND EXTRINSIC ARTIFACT
Extrinsic Artifact
•
•
•
•
•
•
High impedance
Electrode ‘popping’
Mains interference
Polarity reversal
Over amplification
Incorrect referencing
Intrinsic Artifact
Physiological:
•
•
•
•
•
Eyes movements, Blinks
Muscle/ movement
Heart: ECG pick-up
Sweat: LF artifact
Respiration: LF artifact
Pathological:
Bruxism, excessive spindling, muscle
fasciculation, seizure activity, etc
This is not strictly artifact but definitely needs to be recognised
5
22
ARTIFACT RESOLUTION
• Differential Amplification
• Referencing
• Impedance
• Polarity
• Filtering
• Ground and Reference Electrodes
23
DIFFERENTIAL AMPLIFICATION
Differential amplifiers reduce or eliminate environmental noise by inverting and
subtracting the reference electrode signal from the exploring electrode signal.
Both electrodes carry the same background noise but only the exploring electrode
will pick up the additional EEG signal which will be retained after differential
amplification.
Environmental
Noise [EN]
EEG + EN
EN
EEG - EN
+
-
Differential
Amplifier
C4
M1
7
24
EXPLORING & REFERENCE ELECTRODES
• Exploring electrodes obtain a signal from a specific area, e.g.
central, frontal or occipital
• Reference electrodes are placed in EEG inactive areas e.g.
mastoid process and are used to compare with the exploring
electrode on the opposite side of the skull
F4:M1
C3:M2
8
25
PATIENT GROUND &
2ND REFERENCE ELECTRODES
PGND:
2nd Reference Electrode
26
RE-REFERENCING
• Some systems allow you to add additional channels to your montage
by referencing the signal between any of the electrodes
• If both M1 and M2 electrodes should be lost:
-F3 and C3 could be re-referenced to O2
-F4 and C4 could be re-referenced to O1
27
REF-REFERENCING
In this example, although A(M)2 and A(M)1 are intact, a new channel has been
created by selecting F3 on the montage and referencing to O2.
The new channel F3O2 appears at the top of the display
28
IMPEDANCE
• Impedance is the resistance to the flow of an electrical current
• The lower the impedance the better the signal quality
• High impedance decreases the amplitude of a signal
• Skin preparation is a major determinant of electrode impedance
AASM recommended impedance < 5kΩ (EMG may be as much as 10kΩ)
12
29
FACTORS INFLUENCING IMPEDANCE [Ω]
• Stratum corneum (outermost layer of
epidermis- mainly dead skin cells and
sebum)
• Skull thickness
• Length, gauge and continuity of the
electrode wire
• To reduce the impedance you abrade
the skin thus reducing the thickness
of the stratum corneum
13
30
ELECTRODE ‘POPPING’ & SWEAT SWAY
• Electrode ‘popping’ occurs when the electrode has partially lost
contact with the skin and air forms a barrier to the conduction of the
signal
• Sweat between the skin and the electrode will also affect the signal
baseline ‘Sweat Sway’
31
SIGNAL POLARITY
• A negative output signal causes an upward deflection on the visible
trace
• A positive output signal produces a downward deflection on the
visible trace
• Occasionally the signal is very obviously inverted from the outset or
sometimes spontaneously inverts during the recording- this needs to
be recognised
15
32
FILTERS
• Filters give us the ability to focus on only the signal
frequencies that we want to see
• They attenuate (reduce) unwanted signals
• Different filters can be applied to each channel to allow
us to view the desired frequency range of each type of
signal, EEG, EMG, ECG etc
• They can also be used (carefully) to remove signal
artifact but caution should be applied as some of the
desired physiological can be lost through over-filtering
16
33
EEG FREQUENCIES
• Beta: ≥14 Hz
(normal, waking anterior)
• Alpha: 8 – 13 Hz
(normal, waking posterior)
• Theta: 4 – 7 Hz
(normal drowsy, light sleep)
• Spindles & K complexes
• Delta: <4Hz
(normal deep sleep)
34
LOW FREQUENCY FILTER (LFF)
• Also known as the ‘high pass’ filter
• The LFF allows higher frequencies to pass unchanged
• Lower frequencies are attenuated (reduced)
• LFF can be used to reduce respiratory artefact and sweat sway
• LFF should be used with caution as it may also attenuate desired
frequencies such as slow wave sleep if applied inappropriately
18
35
LFF ON EEG
• LFF can be used to reduce respiratory artefact and sweat sway
• LFF should be used with caution as it may also attenuate desired
frequencies such delta waves
LFF set at 0.3 (AASM)
19
36
HIGH FREQUENCY FILTER (HFF)
• Also known as the ‘low pass’ filter
• The HFF allows slower waves to pass through
unchanged and attenuates higher frequencies
• The HFF can eliminate muscle artefact or external
electrical artefact in EEG channels
• It may also remove desired high frequencies such as
arousals or sleep spindles
20
37
HFF ON EEG
•
The HFF can eliminate muscle artefact or external electrical artefact in EEG channels
•
It may also remove desired high frequency waveforms such as sleep spindles
NB: HFF is usually set at 35Hz for EEG/EOG (AASM)
21
38
50HZ/NOTCH FILTER
• 50Hz artifact is a high frequency artifact which can be caused by high
signal impedance, interference from external electrical equipment
and poor application of electrodes 50Hz noise due to poor electrode application
• Notch filters attenuate specific frequencies (in reality they attenuate a
small range around the desired frequency)
• A 50Hz filter will also attenuate important signals in this range such as
muscle activity or epileptiform activity
22
39
FILTER SETTINGS (AASM)
LFF Hz
HFF Hz
EEG
0.3
35
EOG
0.3
35
EMG
10
70
ECG
0.3
70
Respiration
0.1
15
Snoring
10
100
23
40
ECG PICK-UP & ELIMINATION
• ECG is a much larger amplitude signal than EEG and may be picked up
if the mastoid electrodes are positioned too low on an obese patient
• Some systems have the ability to differentially reference channels to
the ECG channel which will help cancel out any extraneous ECG pickup on the EEG, EOG and EMG.
• An ECG signal will also be present on the Leg EMG if only one
electrode is placed on each leg instead of two
41
Same epoch with ECG Elimination applied to all EEG channels
42
IDENTIFYING AND RESOLVING INTRINSIC AND EXTRINSIC
ARTIFACT
Extrinsic Artifact
•
•
•
•
•
•
High impedance
Electrode ‘popping’
Mains interference
Polarity reversal
Over amplification
Incorrect referencing
Intrinsic Artifact
Physiological:
• Eyes movements, Blinks
• Muscle/ movement
• Heart: ECG pick-up
• Sweat: LF artifact
• Respiration: LF artifact
Pathological:
Bruxism, excessive spindling, muscle
fasciculation, seizure activity, body
rocking, head banging, sleep walking,
RBD…
26
43
EXTRINSIC ARTIFACT
HF artifact on C3M2 & O1M2 Channels
Cause:
Poor electrode contact M2 (electrode common to both channels)
Solutions: 1. Reapply electrode
2. Apply 50Hz notch filter to M2
3. Reference C3 and O1 to M1 electrode
27
44
Extrinsic Artifact:
LF artifact on O1M2
Cause:
Sweat & O1 lead too tight, being pulled on inspiration, affecting
impedance
Solutions: 1. loosen the lead from the bundle at the top of the head
2. Apply LFF to this channel
28
45
Extrinsic Artifact:
Inverted ECG signal
Cause:
ECG Electrodes correctly positioned but leads plugged into wrong
polarity port + / -
Solutions: 1. Invert signal display for this trace
2. Swap ECG leads into correct polarity port - / + on patient interface
29
46
Extrinsic Artifact:
K Complex with arousal V’s electrical artifact M2
47
Extrinsic Artifact:
Irregular abdominal effort signal
Cause:
Abdominal band too loose, gain turned up too much to compensate
Solutions: 1. Tighten Abdominal belt and then reduce gain
31
48
Extrinsic Artifact:
Periods of airflow and effort cessation alternating with periods of airflow with
‘paradoxical’ respiratory effort
Cause:
Abdominal band polarity reversed (piezo-electric belts)
Solution: Reverse polarity of abdominal belt (see below)
32
49
Extrinsic Artifact:
LF artifact on C3M2channel
Cause:
Air trapping or poor contact of C3 electrode causing electrode ‘popping’
Solutions: 1. Reapply electrode if necessary
2. Remove trace from recording view if C4-M1 giving good signal
33
50
Extrinsic Artifact:
LF artifact on C3M2 and O1M2 channels
Cause:
Air trapping or poor contact of M2 electrode causing electrode ‘popping’
Solutions: 1. Reapply electrode if necessary, inject more gel into electrode
2. Re-reference C3 and O1 to M1
34
51
INTRINSIC ARTIFACT EXAMPLES
Physiological Artifact: Eye movement pick-up on EEG
Eyes open left to right
Eyes open up and down
Eye blinks
35
52
Physiological Artifact:
HF muscle activity on EEG, EOG and EMG signals
Jaw clenching during bio-calibration
36
53
Physiological Artifact:
ECG pick-up on single channel leg EMG
Cause:
One electrode on L leg, one on R leg gives summation of EMG
activity on both legs but also acts as 2 lead ECG channel.
Solutions: Use 2 electrodes on each leg, separate L Leg EMG from R Leg
Alternatively, record using 2 electrodes on 1 leg only-but this may miss or
underestimate severity of PLMD
37
54
Physiological Artifact:
ECG pick-up on EEG, EOG (and Leg EMG Channel)
Cause:
Solutions:
M1 and M2 electrodes situated on soft tissue rather
than mastoid bone
- Reposition M1 and M2 electrodes
- 2nd Reference to ECG channel
38
55
Physiological Artifact:
LF Sweat artifact on O2M1 EEG
Cause:
Actions:
Patient too hot, sweat affecting impedance
1. Cool the patient down
2. Apply LFF to this channel
39
56
Pathological Artifact:
Cyclical, HF artifact all AC channels
Cause: Bruxism: Cyclical muscle activity picked up on EEG, EOG & EMG
Actions: None, Tech comment and print epoch for PSG report
40
57
Pathological Artifact:
Episodes of HF simultaneous ‘artifact’ all channels
Cause:
Rhythmic Movement Disorder , body rocking sometimes seen in ADHD
and psychological disturbances
Actions: None necessary, Tech comment and print for PSG report
58
Pathological Artifact:
Cyclical bursts of faster EEG waveforms
Cause:
Excessive sleep spindles: often seen in benzodiazepine use
Actions: None necessary, Tech comment and print for PSG report
42
59
Pathological Artifact:
Atypical waveforms on ECG channel
Cause:
Cardiac arrhythmia: Intermittent and runs of PVCs,
Solutions: None necessary, Tech comment and print epoch for PSG report
NB: A prolonged run of PVC’s may be cause for emergency protocol
initiation especially if there is no mention of cardiac problems in the
patient’s notes.
43
60
Pathological Artifact:
HF artifact superimposed on LF waveforms during N3 sleep
Cause: Movement: Movement during N3 sleep e.g. position change or even sleep walking
This is muscle activity on delta waveforms.
Note patient is in N3 sleep before and after 14 second event
Actions: None necessary, Tech comment and print epoch for PSG report
44
61
Pathological Artifact:
High amplitude spike and wave artifact on EEG
High muscle tone on Chin and Leg EMG
Cause:
Seizure: Characteristic spike and wave activity on EEG
Actions: Follow protocol for seizures, Tech comment and print epochs for PSG
report
NB Prolonged seizures (>5mins) can be life threatening
45
62
Pathological Artifact:
Irregular, prolonged bursts of HF activity on Leg EMG
Cause:
REM Behaviour Disorder: Limb movements due to lack of REM atonia
Actions:
Tech note and print epoch for PSG report
46
63
A FEW TECHNICAL
TIPS-:
64
ELECTRODE INTEGRITY & ORIENTATION
O1
O2
The electrode wires should
be kept as short as possible,
in good condition and all of
equal length and type
C4
C3
M2
M1
F4
F3
R.EOG
L.EOG
48
65
Electrode orientating and gathering:
Always ask yourself –”where does the headbox end up in relation to the patient?”
Gather up and direct electrode wires towards this. This is not only more comfy for
the patient (they not lying on a bunch of wires) but it also reduces pulling and
displacement of the sensors and gives a longer ‘umbilicus’.
Soft Velcro loop
holds electrodes in place- take some
time to equalise these so they have
equal tension and make sure you ask
the patient to twist their head round
and make sure nothing is pulling
Orientating leads towards CZ
and gathering at the top of the head
pointing directly towards the head box
headbox
66
Electrode Application Tips
Electrode gluing with gauze
-Advantages include, makes gluing a bit quicker, mainly much less glue in hair and on
your fingers!
10-20 Paste
Electrode head fits
filled electrode
Ring of collodion on the gauze with a
in middle of glue
space for the electrode head.
To remove use acetone with cotton wool to soak gauze off.
67
Take time to equalise and sort all wires out:Try not to have one pulling more than another.
Try not to trap hair in the velcro loop
Make sure there are none swinging in the breeze.
They should all be attached at either end to the patient and the headbox!
Unless they are colour coded, apply and plug-in as you go.
68
The quick release leg loop- to prevent the loss of leg electrodes
Quick release on kick
69
Golden Rules:
• Keep your equipment in good working
• Check and replace any faulty electrodes/sensors
• Good skin preparation and careful cleaning &
application of electrodes and sensors is paramount
• Always perform bio-calibration
• Re-check impedances prior to lights out and during the
study
• Don’t wake the patient up to change electrodes unless
really necessary
• Only use filters to attenuate artifact as a last resort
70
FURTHER READING
• The AASM annual for the Scoring of Sleep and Associated
Events: Rules, Terminology and technical Specifications Version
2.1.
American Academy of Sleep Medicine (2014)
• Essentials of Polysomnography 2nd Edition.
William H. Spriggs; Jones & Bartlett Publishers (2014)
• Essentials of Sleep Technology
Richard S. Rosenberg; American Academy of Sleep Medicine (2010)
• Sleep Medicine Textbook,
European Sleep Research Society (2014)
71
ANY QUESTIONS?
72
Scoring sleep using AASM guidelines: A brief introduction
Ms. Elizabeth Hill
Paediatric Respiratory Physiology
Department of Respiratory&Sleep Medicine
Royal Hospital for Sick Children
9 Sciennes Road, Scotland
EH9 1LF Edinburgh
UNITED KINGDOM
[email protected]
SUMMARY
Early pioneers used EEG to “look inside” the brain using sleep. Over time, this was developed into
polysomnography (PSG), which was first used to define sleep stages in the 1960s. PSG is now the
recognised gold-standard technique for measuring sleep, allowing classification of sleep stages,
assessment of sleep architecture and diagnosis of sleep disorders.
This workshop aims to review the criteria for scoring of sleep stages as described in The AASM Manual
for Scoring of Sleep and Associated Events Version 2.1 (American Academy of Sleep Medicine, 2014).
The benefits and drawbacks of these guidelines will be discussed. Delegates will have the opportunity
to apply the current guidelines in small groups during a practical exercise, identifying sleep stages using
real-world examples.
EVALUATION
1.
Which of the following statements is not true regarding alpha rhythm?
a. The frequency is 8-13Hz
b. It is commonly observed during stage W with the eyes closed
c. It can be seen most clearly on the frontal EEG
d. Around 10% of individuals do not generate alpha rhythm
2. According to the AASM V2.1 guidelines, when scoring stage N1:
a. The EEG shows a low voltage, mixed frequency pattern of 4-7Hz
b. Vertex sharp waves may be seen, predominantly on the central EEG
c. N1 should not be scored after N3, unless there is an intervening arousal
d. All of the above
3. Stage N2 should be scored:
a. When a spindle or K complex is present in the first half of an epoch
b. After a page of N3 if it does not meet the criteria for W, N3 or R
c. Both A and B
d. Neither A nor B
4. Which of the following is a scoring criteria for stage N3?
a. Absence of sleep spindles
b. Slow waves of 0-2Hz and ≥75µV in ≥20% of the epoch
c. Low voltage, mixed frequency EEG
d. Transient muscle activity
73
5. Which of the following features are not required to score “Definite Stage R”?
a. Very low chin EMG tone (atonia)
b. Sawtooth waves on the central EEG
c. Rapid eye movements on the EOG
d. Low amplitude, mixed frequency EEG without spindles or K complexes
74
SCORING SLEEP USING AASM GUIDELINES:
A BRIEF INTRODUCTION
Lizzie Hill
BSc RPSGT EST
Specialist Respiratory Clinical Physiologist, Royal Hospital for Sick Children, Edinburgh
Final Year PhD Research Student, The University of Edinburgh
75
Conflict of interest disclosure
I have no, real or perceived, direct or indirect conflicts of interest that relate to this
presentation.
Affiliation / financial interest
Nature of conflict / commercial company name
Tobacco-industry and tobacco corporate affiliate related
conflict of interest
None
Grants/research support (to myself, my institution or
department):
None
Honoraria or consultation fees:
None
Participation in a company sponsored bureau:
None
Stock shareholder:
None
Spouse/partner:
None
Other support or other potential conflict of interest:
None
This event is accredited for CME credits by EBAP and speakers are required to disclose their potential conflict of interest going
back 3 years prior to this presentation. The intent of this disclosure is not to prevent a speaker with a conflict of interest (any
significant financial relationship a speaker has with manufacturers or providers of any commercial products or services relevant to
the talk) from making a presentation, but rather to provide listeners with information on which they can make their own judgment.
It remains for audience members to determine whether the speaker’s interests or relationships may influence the presentation.
Drug or device advertisement is strictly forbidden.
76
AIMS
• To review criteria for staging sleep as defined by international
guidelines (AASM V2.1, 2014).
• To discuss the benefits and drawbacks of these guidelines.
• To apply the current AASM guidelines by identifying sleep
stages during a practical exercise.
77
EXPERIENCE
• Completely new to scoring?
• A little experience of scoring PSG?
• Regularly scoring PSG?
• RPSGT (Registered Polysomnographic Technologist)?
• EST (ESRS Somnologist – Technologist)?
78
INTRODUCTION
• Early pioneers used EEG to “look inside” brain using
sleep
• Developed into polysomnography
• Rechtshaffen & Kales used PSG to define stages of
sleep
• PSG now standard technique for measuring sleep
Deak & Epstein, 2009
79
POLYSOMNOGRAPHY
• Objective measurement of sleep & wake
(overnight or during the day)
• Gives information on
–
–
–
–
Duration/amount of sleep
Patterns of sleep
Quality of sleep
Behaviours during sleep
• Information from PSG can be used to define sleep
stages
80
POLYSOMNOGRAPHY
Sensors applied in standard positions
Workstation 1
Studies scored using
standard rules by
skilled technolologist
This workstation
81
AASM MONTAGE
82
SCORING SLEEP STAGES
• Based on unit of epoch
– 30s in most labs
• Each epoch reviewed in turn and assessed as a
whole for its sleep stage
• In some situations, the page before or after can
influence the decision
• To score a certain stage of sleep at least half the
epoch (15 seconds) must be classified as that stage
83
SCORING POLYSOMNOGRAPHY
Scroll through study several times:
– Sleep staging – 30s epoch
– EEG arousals – 30s epoch
– Respiratory events – 2min / 5min epoch
• 10min epoch to screen for Cheyne-Stokes
– Periodic leg movements – 5min epoch
84
SCORING CRITERIA
• Each stage of sleep defined by certain
characteristics
– Rechtschaffen and Kales (1968)
– AASM Manual for the Scoring of Sleep and Associated Events (2007)
•
•
•
•
Version 2.0
Version 2.0.1, 2.0.2
Version 2.0.3
Version 2.1
2012
2013
January 2014
July 2014
85
AASM VERSION 2.1 - 2014
• Current version of
guidelines
• Published July 2014
• Online & print versions
86
BENEFITS OF AASM GUIDELINES
• Standardised international guidelines
• Comprehensive manual
–
–
–
–
Setting up lab
Training staff
Reference guide
Lab accreditation
• Flexible online format
– Updated annually
87
LIMITATIONS OF AASM GUIDELINES
• Staggered implementation → variation between
centres
• Frequent revisions → “shifting goalposts”
– Many changes related to US Medicare reimbursement
• Based on scoring full PSG
– AASM also recommends use of portable monitoring
Collop et al, JCSM, 2007
– Transferable to limited studies?
– ERS Task Force TF-2014-02 (2014-2016)
88
SCORING SLEEP STAGES
89
ADULT SLEEP
• Comprises 2 states
– NREM : non-rapid eye movement sleep
– REM : rapid eye movement sleep
• Alternate cyclically over a period of sleep
– Ultradian rhythm
• Sleep stages with distinct, measurable features
90
INFANT SLEEP
• 2 distinct stages:
– Active sleep (REM)
– Quiet sleep (NREM)
• Normal for infants < 3
months to have sleeponset REM (active sleep)
• NREM (quiet sleep)
becomes clearly
demarcated aged 3 – 6
months
91
SCORING SLEEP STAGES
This session based on adult scoring rules –
AASM Version 2.1 (2014)
92
STAGE W
• Alpha rhythm / posterior dominant rhythm
– 8-13Hz
– Majority of individuals(~10% do not generate alpha)
– clearest on occipital EEG
AND / OR
• Other findings consistent with W
– Eye blinks
– Rapid eye movements (REMs) with normal/high chin EMG
– Reading eye movements
93
STAGE W – EYES OPEN
From AASM
94
STAGE W – EYES CLOSED
Eye blinks
Alpha rhythm
From AASM
95
STAGE N1
Appearance of any of:
• Low amplitude, mixed frequency EEG (LAMF)
– 4-7Hz
• Vertex sharp waves (V waves)
– Central EEG
– <0.5s duration
• Slow eye movements (SEMs)
96
STAGE N1
• Score N1 if majority of stage meets criteria
for N1 in the absence of evidence for any
other sleep stage
• Keep scoring N1 until there is evidence of
another sleep stage
– Usually W, N2 or R
97
STAGE N1
From AASM
98
STAGE N2
Characteristic waveforms:
• Sleep spindle
– fast burst (≥0.5s) of 11-16Hz activity
– clearest on central EEG
• K complex
– -ve EEG deflection followed by +ve (≥0.5s)
– clearest on frontal EEG
99
STAGE N2
• Start scoring N2 if a K complex and/or sleep spindle
is present in the first half of the epoch or last half of
preceding epoch
– “Definite stage N2”
• Continue to score N2 in absence of spindle/Kcomplex if no arousals
• Epochs after a page of N3 are scored as N2 if they
do not meet criteria for W, N3 or R
– Do not score N1 after N3
100
STAGE N2
• Stop scoring N2 when
– Transition to stage W, N3 or R
– Arousal followed by LAMF (N1)
– Major body movement followed by SEM and LAMF
(N1)
101
K complex
STAGE N2
Sleep spindles
From AASM
Low voltage, mixed frequency background EEG
102
STAGE N3
• Slow waves in ≥20% (≥6s) of epoch
– 0-2 Hz
– ≥75µV in amplitude in frontal EEG
– Irrespective of age
• Do not confuse K complexes with slow waves
– K complexes separated in time
– slow waves tend to occur in runs
– K complexes develop into slow waves at transition from N2 to N3
• Spindles can persist into N3
103
STAGE N3
Delta activity / slow waves
From AASM
104
STAGE R
Characteristic waveforms:
• Bursts of rapid eye movements (REMs) on EOG
• Very low amplitude EMG (atonia)
• Sawtooth waves
– clearest on central EEG
– Often precede bursts of REMs
• Phasic twitches on EMG
Adapted from AASM
– Transient muscle activity
105
STAGE R
• “Definite stage R” scored in epochs with ALL of
– LAMF without spindles/K complexes
– Low chin EMG tone (atonia)
– REMs
• Pages before and after “Definite stage R” scored as
R in absence of REMs with ALL of
–
–
–
–
LAMF without spindles/K complexes
Low chin EMG tone (atonia)
No arousal
No SEMs
• R takes precedence over N2
106
STAGE R
• Stop scoring R if ANY of
– Transition to W or N3
–  EMG tone and meets criteria for N1
– Arousal followed by LAMF and SEMs (N1)
– Major body movement followed by LAMF and SEMs
without a sleep spindle or K complex (N1)
– Sleep spindle or K complex in first half of epoch in absence
of eye movements (even if chin EMG still low)
107
Burst of rapid eye movements
STAGE R
Delta activity / slow waves
From AASM
Phasic twitch
Loss of muscle tone (atonia)
108
HYPNOGRAM
• Once scored, all sleep stages collated to produce
hypnogram
• Visual representation of sleep architecture
109
NORMAL SLEEP
• Normally enter sleep through NREM in adults
• Cycles with REM sleep at approx. 90 minute
intervals (90 – 110 minutes)
• 4-5 REM periods in young adults
• Short awakenings are normal
110
SLEEP ARCHITECHURE
• Normal
• Severe OSAHS
• Treatment with
CPAP
111
PRACTICAL SESSION
• Split into groups of 3 – 4
• Set of laminated sample epochs
• Assess each example as a group
– EEG frequency
– Distinct, measurable features
• Decide which sleep stage to score
112
EXAMPLE 1
Delta activity / slow waves
From AASM
113
EXAMPLE 2
Delta activity / slow waves
From AASM
114
EXAMPLE 3
Delta activity / slow waves
From AASM
115
EXAMPLE 4
Delta activity / slow waves
From AASM
116
EXAMPLE 5
Delta activity / slow waves
From AASM
117
EXAMPLE 6
Delta activity / slow waves
From AASM
118
EXAMPLE 7
Delta activity / slow waves
From AASM
119
EXAMPLE 8
Delta activity / slow waves
From AASM3.73
120
EXAMPLE 9
Delta activity / slow waves
From AASM
121
EXAMPLE 10
Delta activity / slow waves
From AASM
122
EXAMPLE 11
Delta activity / slow waves
From AASM
123
EXAMPLE 12
Delta activity / slow waves
From AASM
124
EXAMPLE 13
Delta activity / slow waves
From AASM
125
EXAMPLE 14
Delta activity / slow waves
From AASM
126
EXAMPLE 15
Delta activity / slow waves
From AASM
127
CONCLUSION
• Electrophysiological changes during sleep can be
measured using polysomnography.
• Distinct, measurable electrophysiological features
are used to define different stages of sleep.
• Classifying sleep stages allows us to examine sleep
architecture.
• International guidelines for sleep staging are
available.
128
FURTHER READING
• The AASM annual for the Scoring of Sleep and
Associated Events: Rules, Terminology and
technical Specifications Version 2.1.
American Academy of Sleep Medicine (2014)
• Essentials of Polysomnography 2nd Edition.
William H. Spriggs; Jones & Bartlett Publishers (2014)
• Essentials of Sleep Technology
Richard S. Rosenberg; American Academy of Sleep Medicine (2010)
129
FURTHER TRAINING
• Practical Polysomnography – Edinburgh, UK
– Various dates
• Edinburgh Sleep Medicine Course – Edinburgh, UK
– March 2016
• European Sleep School – Orihuela Costa, Spain
– Various dates
• International Sleep Medicine Course – Cardiff, UK
– June 2016
130
Any questions?
[email protected]
[email protected]
www.ed.ac.uk/clinical-sciences/sleep-research
uk.linkedin.com/in/lizziehillsleeptechservices
131
Recommended reading list and E-learning resources
1. The AASM annual for the Scoring of Sleep and Associated Events: Rules, Terminology and
technical Specifications. Version 2.1 American Academy of Sleep Medicine (2014)
2. Bassetti C., Dogas Z., Peigneux P., Sleep Medicine Textbook (European Sleep Research
Society (ESRS), Regensburg, (2014)
3. Spriggs W. H.; Essentials of Polysomnography, Jones & Bartlett Publishers (2008)
4. Rosenberg R. S. Essentials of Sleep Technology, American Academy of Sleep Medicine
(2010)
5. Butkov N., Atlas of Clinical Polysomnography Second Edition (Two‐volume Set), Media
matrix, (2011)
6. Jasper, H.H. The ten twenty system of the International Federation. Electroencephalography
and Clinical, Neurophysiology, 1958, 10:371‐375.
7. Chokroverty S., Polysomnographic technique: An overview. In: Sleep disorders medicine, 2nd
ed. Boston Butterworth Heinemann (1999)
8. Tyner F, Knott J, Mayer W Jr., Fundamentals of EEG technology, Volume 1:
Basic concepts and methods. New York: Raven Press; (1983).
9. Lee‐Chiong T, Sateia M, Carskadon M, Sleep medicine, Hanley & Belfus, 2002
10. Spriggs W. H, Essentials of Polysomnography 2nd Edition. Jones & Bartlett Publishers (2014)
11. Sleep Medicine Textbook; European Sleep Research Society (2014)
132
Faculty disclosures
There are no faculty disclosures for this workshop.
133
Faculty contact information
Prof. Dr Simone De Lacy
European Sleep School
Orihuela Costa
SPAIN
[email protected]
Ms. Elizabeth Hill
Paediatric Respiratory Physiology
Department of Respiratory&Sleep Medicine
Royal Hospital for Sick Children
9 Sciennes Road, Scotland
EH9 1LF Edinburgh
UNITED KINGDOM
[email protected]
Dr Andrew Morley
Royal Hospital for Sick Children
79 Hardgate Rd
G51 4SX Glasgow
UNITED KINGDOM
[email protected]
Dr Renata L. Riha
Department of Sleep Medicine
Royal Infirmary Edinburgh
51 Little France Crescent
EH16 4SA Scotland, Edinburgh
UNITED KINGDOM
[email protected]
134
Answers to evaluation questions
Please find all correct answers in bold below
WS2. Data acquisition: what can go wrong? What does it look like when it goes right
– Prof. Dr Simone De Lacy
1. The major determinant of signal impedance is:
a. The length of the electrode lead
b. The preparation of the stratum corneum
c. The thickness of the skull
d. The material used on the electrode surface
2. A low frequency filter set at 0.3 Hz will do all of the following except:
a. Reduce the amplitude of delta activity
b. Leave faster frequencies intact
c. Reduce the amplitude of sleep spindles
d. Reduce respiratory artifact
3. A ‘Low Pass’ filter set at 35 Hz will do all of the following except:
a. Increase the amplitude of sleep spindles
b. Reduce muscle artefact
c. Leave alpha, delta and theta frequencies intact
d. Reduce external electrical artifact
4.
Which of the following is an example of physiological artifact on an EEG channel:
a. ECG signal on C4:M1
b. Electrode ‘popping’
c. 50 Hz frequencies
d. 0.1 Hz frequencies
5. All of the following might be used to reduce signal artifact except:
a. Cleaning and scarification of the skin
b. Notch filters
c. Cooling the patient by lowering the ambient temperature
d. Waking the patient to remove and replace a dislodged mastoid electrode
WS3. Scoring sleep using AASM guidelines: A brief introduction - Ms. Elizabeth Hill
1. Which of the following statements is not true regarding alpha rhythm?
a. The frequency is 8-13Hz
b. It is commonly observed during stage W with the eyes closed
c. It can be seen most clearly on the frontal EEG
d. Around 10% of individuals do not generate alpha rhythm
2. According to the AASM V2.1 guidelines, when scoring stage N1:
a. The EEG shows a low voltage, mixed frequency pattern of 4-7Hz
b. Vertex sharp waves may be seen, predominantly on the central EEG
c. N1 should not be scored after N3, unless there is an intervening arousal
d. All of the above
3. Stage N2 should be scored:
a. When a spindle or K complex is present in the first half of an epoch
b. After a page of N3 if it does not meet the criteria for W, N3 or R
c. Both A and B
d. Neither A nor B
4. Which of the following is a scoring criteria for stage N3?
a. Absence of sleep spindles
b. Slow waves of 0-2Hz and ≥75µV in ≥20% of the epoch
c. Low voltage, mixed frequency EEG
d. Transient muscle activity
5. Which of the following features are not required to score “Definite Stage R”?
a. Very low chin EMG tone (atonia)
b. Sawtooth waves on the central EEG
c. Rapid eye movements on the EOG
d. Low amplitude, mixed frequency EEG without spindles or K complexes