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Questions and Answers
What is the main reason for not eliminating the 10-second cutoff for defining electrographic seizures?
What is the main reason for not eliminating the 10-second cutoff for defining electrographic seizures?
Which group is this terminology primarily intended to serve?
Which group is this terminology primarily intended to serve?
Which of the following terms best categorizes EEG findings in this terminology?
Which of the following terms best categorizes EEG findings in this terminology?
What does the terminology specifically exclude from its intended use?
What does the terminology specifically exclude from its intended use?
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Which aspect is considered important when defining EEG findings related to epilepsy surgery?
Which aspect is considered important when defining EEG findings related to epilepsy surgery?
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What does the term 'ictal' refer to in EEG literature?
What does the term 'ictal' refer to in EEG literature?
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In the context of EEG voltage measurements, what is the basis for these measurements?
In the context of EEG voltage measurements, what is the basis for these measurements?
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What is meant by the term 'consistent' in the context of discharges in periodic patterns?
What is meant by the term 'consistent' in the context of discharges in periodic patterns?
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Which of the following frequency bands is not specifically mentioned as predominant during awake or stimulated states?
Which of the following frequency bands is not specifically mentioned as predominant during awake or stimulated states?
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In assessing EEG background symmetry, what is indicated by 'mild asymmetry'?
In assessing EEG background symmetry, what is indicated by 'mild asymmetry'?
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Study Notes
American Clinical Neurophysiology Society (ACNS) Standardized Critical Care EEG Terminology 2021
- This terminology is intended for use in all ages except neonates.
- The document is mostly compatible with the 2017 multinational revised glossary of terms.
- The document utilizes "ictal" to refer to EEG patterns during epileptic seizures, both clinical and electrographic.
- "Hz" is used as an abbreviation for "per second" for all periodic or rhythmic patterns.
- All voltage measurements in this document are based on peak to trough in a standard 10–20 longitudinal bipolar recording.
- The term "consistent" or "consistently" refers to >80% of instances.
EEG Background
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Symmetry:
- Describes the voltage and frequencies in relation to each hemisphere.
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Symmetricindicates equal voltage and frequency bilaterally. -
Mild Asymmetryindicates consistent asymmetry in voltage with a 1 Hz frequency asymmetry.
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Predominant Background Frequency
- Assesses the frequency band that is most present when the patient is awake or after stimulation.
- Options include: Beta, Alpha, Theta, and Delta.
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Posterior Dominant (“Alpha”) Rhythm
- Must be demonstrated to attenuate with eye opening.
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Presentif the frequency can be determined precisely. -
Absentif the pattern is not captured. -
Unclearif the presence of the rhythm is ambiguous.
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Continuity
- Assesses how continuous the background pattern appears during the recording.
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Continuousindicates the pattern is consistent in the majority of the recording. -
Nearly Continuousindicates that the pattern is continuous but there are occasional periods of attenuation or suppression. -
Intermittentindicates that the pattern is present in more than 50% of the record. -
Suppression/attenuationindicates the pattern is present in less than 50% of the record.
EEG Patterns
- Electrographic seizures (ESz), electrographic status epilepticus (ESE), electroclinical seizures (ECSz), and electroclinical status epilepticus (ECSE) are defined based on the “Salzburg criteria.”
- Brief potentially ictal rhythmic discharges (BIRDs) are included based on recent publications.
- Ictal-interictal continuum (IIC) has been proposed.
- Other definitions include identical bursts, state changes, cyclic alternating pattern of encephalopathy (CAPE), and extreme delta brush (EDB).
Research Significance
- A database incorporating the ACNS terminology was developed for clinical and research purposes.
- It is available on the ACNS website.
- The database has allowed for multicenter investigations into the clinical significance of rhythmic and periodic patterns (RPPs) in critically ill patients.
- Patterns including lateralized rhythmic delta activity (LRDA) have been shown to be associated with acute seizures.
- The association of several patterns with seizures was defined in a multicenter cohort of almost 5,000 patients.
- Studies have shown that several modifiers within the nomenclature have clinically relevant meaning.
Definitions
- The document provides definitions for various EEG patterns and terms.
- All definitions are based on extensive discussion and consensus among experts.
- Electronic voting was used for issues that did not have complete consensus.
- The document includes schematic diagrams of the core features and principles of the patterns.
- Supportive EEG examples from 30 cases are available as Supplemental Digital Content.
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Description
This quiz tests your knowledge of the Standardized Critical Care EEG Terminology as defined by the American Clinical Neurophysiology Society in 2021. You will learn key terms, definitions, and principles that are applicable across all ages (excluding neonates) regarding EEG interpretations, particularly in critical care settings.
