ACNS Guidelines Flashcards
ACNS Guideline 1
Minimum Technical Requirements for Performing Clinical Electroencephalography
ACNS Guideline 2
Guidelines for Standard Electrode
Position Nomenclature
ACNS Guideline 3
A Proposal for Standard Montages to
be Used in Clinical EEG
ACNS Guideline 4
Recording Clinical EEG on
Digital Media
ACNS Guideline 5
Minimum Technical Standards for
Pediatric EEG
ACNS Guideline 6
Minimum Technical Standards for EEG
Recording in Suspected Cerebral Death
ACNS Guideline 7
Guidelines for Writing EEG Reports
ACNS Guideline 12
Guidelines for Long-Term Monitoring
for Epilepsy
ACNS Guideline 13
Guideline on
Continuous Electroencephalography Monitoring in Neonates
ACNS Guideline 16
Standardized EEG Terminology and Categorization for the Description of Continuous EEG Monitoring in Neonates
ACNS Guideline 14
Standardized Critical Care EEG Terminology: 2021 Version
Minimum number of** channels **on EEG
16** channels **
additional channels to monitor physiologic activities or look closer at specific brain regions
Advantages of Digital vs Analog EEG equipment
Digital has greater sensitivity, reliability, able to modify view after recording capture, more efficient storage
What ancillary equipment should be included with EEG?
photic lamp
Per IFCN [International Federation of Clinical Neurophysiology] what are EEG electrode requirements?
✔ Free of noise and drift
🚫 attenuate signals between 0.5-70Hz
✔ 21 electrodes placed according to 10-20
✔ isolated ground electrode used
✔ balanced impedances of 10 k Ohms or less
T3 electrode name in the 10-10 system
T7
Hint it’s in the same row as F7
T5 electrode name in the 10-10 system
P7
Hint it’s in the same row as F7
T4 electrode name in the 10-10 system
T8
Hint it’s in the same row as F8
T6 electrode name in the 10-10 system
P8
Hint it’s in the same row as F8
What are the default EEG settings?
Sens @ 5-10 uV/mm
LF 1 Hz
HF 70 Hz
Notch/ 60 Hz filter off
Page rate @ 10-20 sec/ page or 30 mm/sec
Why perform DC and Biocalibration?
Helpful to detect machine issues or if machine settings/ filters are set wrong.
A Basic Data Sheet, associated with every record, should include…
- Patient name and age
- Time & date of the recording
- Name/initials of the technologist
- Indication for the EEG (including description of symptoms or events, and their frequency as well as the time and date of the last seizure/episode (if any))
- Behavioral state of the patient (Awake/ Drowsy/ Sleep/ Confused/ Lethargic/ Coma etc)
- List of neuroactive medications the patient has been taking (including premedication given to induce sleep during EEG)
- Presence/ location of any skull defects - Any additions or modifications to standard electrode placements must be noted
*Any other relevant additional medical history.
**Additional helpful notes include handedness, time of last meal, and if patient was sleep-deprived for the study. Results of previous neurophysiological testing, especially EEGs, should also be included when available.
A baseline EEG should be how long? And include??
- 20 minutes of artifact-free recording (including activation procedures, Eyes Open & Eyes Closed, stimulation to comatose patients)
- view the EEG in at least 3 different montages (including at least one bipolar and one referential montage)
Difference between Longitudinal Bipolar and Transverse Bipolar montages?
Longitudinal Bipolar = electrodes linked front to back
Transverse Bipolar = electrodes linked left to right
characteristics of the 10-10 alphanumeric nomenclature
1.) The alphabetical part should consist of one but no more than two letters.
2.) The letters should be derived from names of underlying lobes of the brain or other anatomic landmarks.
3.) The complete alphanumeric term should serve as a system of coordinates to locate the electrode.
When to use the 10-10 system
- in patients undergoing presurgical evaluation in the epilepsy monitoring unit
- sometimes during routine EEGs, when attempting to localize the epileptic focus in patients with suspected focal epilepsy
What is the purpose of a montage?
1.) display EEG activity over the entire scalp
2.) allow comparison of activity on the two sides of the brain (lateralization)
3.) aid in localization of recorded activity to a specific brain region
F7/F8 electrodes record activity from
both anterior temporal and frontal regions.
bipolar montage using FT9/FT10 (or sphenoidal electrodes) can localize activity more precisely to
the anterior temporal region
montages that include closely spaced parasagittal electrodes (FC1/FC2, FCz, C1/C2, CP1/CP2, and CPz) can be very helpful in patients with
suspected mesial frontal lobe epilepsy
Minimum sampling rate
256Hz
*Higher rates, such as 512 Hz, are preferable to prevent aliasing on modern high-resolution computer screens
Digitization should use a resolution of at least
16 bits per sample including any sign bit
Foramen ovale electrodes are used
to record from mesial temporal structures without requiring penetration of the skull.
A one- to four-contact flexible electrode is placed in the ambient cistern with the aid of a needle inserted through the foramen ovale.
Downside to Foramen ovale electrodes
are not as close to hippocampal structures as intracerebral electrodes and do not allow as large a recording field as grids and strips
but detect mesial temporal EEG discharges better than sphenoidal and scalp electrodes.
When to use foramen ovale electrodes
When scalp recordings are ambiguous, foramen
ovale electrodes offer a less invasive alternative to a more complete intracranial evaluation
or can be used in association with grids and strips.
Foramen ovale electrodes may also be constructed from MRI-compatible metals.
Sphenoidal locations are used
to record epileptiform activity from the mesial or anterior aspects of the temporal lobe in the region of the foramen ovale.
Disk Electrode preferred application technique
—Collodion technique is currently the only
method that will insure a stable long-term recording.
—Should be dried slowly to make a film over the electrode, which prevents the electrode jelly from drying out.
—Underlying skin should not be unduly abraded when electrodes are to remain in place several days. Electrode jelly that is used should not contain irritants or dry out quickly. A felt pad may be used under a disk electrode to prevent pressure breakdown of
the skin.
What application method is NOT Recommended for LTM
Application by electrode paste alone
With CHILDREN when are Photic and Hyperventilation recommended during the recording?
perform hyperventilation at the beginning and photic stimulation at the end of the recording to maximize spontaneous sleep
TRUE/ FALSE
The use of a single montage throughout the recording of a neonate may be, and often is, sufficient and is preferred in many laboratories.
TRUE
*Nevertheless, a single montage is not always adequate to capture/ display all EEG waveforms. Additional montages should be used when the need arises, for example, to delineate focal abnormalities better.
Parameters most frequently monitored along with EEG in infants are:
heart rate, respirations, and eye movements.
In neonates with invariant patterns, it may be necessary to record for at least:
60 minutes to demonstrate that the tracings are not likely to change.
An adequate neonatal sleep tracing must include:
a full epoch of quiet sleep.
terms such as “electrocerebral silence, isoelectric,” “linear,” and “flat” were replaced in the 1970s with the term:
“electrocerebral inactivity” (ECI)
Electrocerebral inactivity is defined as
the absence of nonartifactual electrical activity over 2 μV (peak to peak) when recording from scalp electrode pairs 10 or more cm apart
EEG recordings in cases of suspected cerebral death have eleven components, which are:
- A Complete Complement of Scalp Electrodes Should Be Used
- Interelectrode Impedances Should Be Less Than 10,000 Ohms but More Than 100 Ohms
- The Integrity of the Entire Recording System Should Be Tested
- Montages for ECI Interpretation Should Include Electrode Pairs At Least 10 cm Apart
- Sensitivity Must Be Increased to a Maximum of 2 μV/mm for At Least 30 Minutes of the Recording
- Filter Settings Should Be Appropriate
- Additional Monitoring Techniques Should Be Used When Necessary to Clarify the Record
- There Should Be No EEG Reactivity to Intense Somatosensory, Auditory, or Visual Stimuli
- Recordings Should Be Performed Only by a Qualified Technologist
- A Repeat EEG Should Be Performed When ECI Is in Doubt
- Recording of Physiologic Variables and Medications
storage on USB flash drives and network access servers are inexpensive, more reliable, and practical for
shorter duration EEG studies
storage on a digital server system is recommended for
inpatient long-term recordings lasting 24 hours or more
primary [digital] data represents
everything that would be traditionally written on paper
along with the waveforms at the time the study was
performed
The three levels are defined of data to be transmitted
Level I - Waveforms Only
Level II - Waveforms or Procedure Annotations, or Both
Level III - Coded Information
A standard format for Routine Scalp EEG reporting should include five sections:
1.) History
2.) Technical Description
3.) EEG Description
4.) Impression
5.) and Clinical Correlation
history section of EEG report:
is an aid to interpretation of the EEG and should be succinct
include the reason for obtaining the recording and any relevant clinical information
as well as identification of the patient and EEG recording
Long-term monitoring for epilepsy (LTME) is used
when
it is important to correlate clinical behavior with EEG
phenomena *Particularly for surgical evaluation
Name the 3 broad reasons for LTME
Diagnosis, Classification/Characterization, Quantification
For high-risk infants, a _____ long EEG is considered inadequate to screen for seizures.
1-hour
Ideally, the EEG technologist should remain at bedside for the _______ of recording to ____________________________.
- first hour
- ensure a high quality recording and to make note of relevant clinical signs.
aEEG
Amplitude-integrated EEG
the most commonly used digital trend for newborns
a Technical Description consists of
background activity, frequency, amplitude, specific patterns, symmetry, focality
Impedances below 100 ohms indicates…
a shunt or short circuit, possibly related to a salt bridge on the scalp
more closely spaced electrodes (like those in 10-10) provdie better…
spatial resolution
Throughout the ACNS guidelines they discourage the use of…
needle electrodes, and in the cerebral death guideline “electrode caps” also are to be avoided
