ACNS 4 (Seizures and Phases)

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Questions and Answers

What does the number of phases equal when there are two baseline crossings?

3 (correct)

Which phase is represented by the color blue in the signal categorization?

Phase 2 (correct)

Phase 1

Phase 3

Phase 0

Which of the following terms is used to describe a phase that is characterized by the greatest voltage?

Dominant phase (correct)

Baseline phase

Typical phase

Sharpest phase

What is the characteristic of spontaneous waves in the categorization?

Never clearly induced Signup and view all the answers

In the categorization of phases, which type of stimulus is not considered nonnoxious?

Noxious stimulation Signup and view all the answers

What must be specified regarding the sharpness of phases?

Both dominant and sharpest phases Signup and view all the answers

Which phase is indicated by the pink color in the signal categorization?

Phase 1 Signup and view all the answers

If a signal shows an unclear phase response to stimuli, how should it be categorized?

Unknown Signup and view all the answers

What qualifies as EDB in an EEG?

Periodic delta brushes Signup and view all the answers

In determining the polarity of EEG patterns, which phase is specified?

Phase with the greatest voltage Signup and view all the answers

Which of the following describes a typical discharge characteristic in relation to PDs?

Periodic delta waves without superimposed activity Signup and view all the answers

What is the primary significance of the term 'sudden onset' in electrographic seizures?

Progression from absent to well-developed within 3 seconds Signup and view all the answers

Which feature does NOT contribute to making an EEG pattern appear more ictal?

Consistent low-frequency oscillations Signup and view all the answers

What categorization encompasses both unilateral and bilateral independent patterns in EEG?

Multifocal patterns Signup and view all the answers

Which morphology characterizes a triphasic wave in EEG analysis?

Negative-positive-negative Signup and view all the answers

What is a characteristic of fast activity in relation to periodic delta waves?

Not associated with the periodicity of delta brushes Signup and view all the answers

What characterizes a biphasic waveform according to the provided definition?

It may appear as triphasic depending on voltage levels. Signup and view all the answers

What does a consistent measurable delay of over 100 ms indicate in EEG terminology?

Anterior-posterior lag or posterior-anterior lag. Signup and view all the answers

Which type of pattern does NOT qualify under the EDB category?

Periodic delta brushes with superimposed fast activity Signup and view all the answers

What is the primary determinant of increased voltage amplitude in an EEG pattern?

Electrographic seizures Signup and view all the answers

Which term should be used when referring to the morphology of certain waveforms like PDs and SW?

Triphasic morphology. Signup and view all the answers

When might a biphasic waveform be observed in an EEG reading?

When the negative phase is too low in voltage to be detected. Signup and view all the answers

What is the implication of observing a lag of less than 100 ms in EEG readings?

No significant delay is present between anterior and posterior derivations. Signup and view all the answers

Which category of waveforms is triphasic morphology NOT applicable to?

Rhythmic delta activity (RDA). Signup and view all the answers

What additional phrase should be added when a waveform has triphasic morphology?

With triphasic morphology. Signup and view all the answers

Which statement best describes the conditions for observing a biphasic waveform?

A negative phase may be obscured, leading to a biphasic appearance. Signup and view all the answers

What is the minimum delay measurement required to classify as anterior-posterior or posterior-anterior lag?

100 ms. Signup and view all the answers

What effect does background activity have on the visibility of a biphasic waveform?

It can obscure the negative phase in some cases. Signup and view all the answers

What qualifies as BIRDs in terms of duration?

Paroxysmal fast activity lasting $ 0.5 to <10 seconds Signup and view all the answers

Which statement best describes the ICTAL-INTERICTAL CONTINUUM (IIC)?

It is synonymous with possible electrographic seizures. Signup and view all the answers

In determining if a pattern qualifies for the IIC, which of the following averaging rates indicates a possible pattern?

0.5 and #1.0 Hz over 10 seconds Signup and view all the answers

Which is not a characteristic of definitively classified BIRDs?

Occurring in the absence of other epileptiform activity Signup and view all the answers

What is the frequent clinical response when a pattern is determined to be ictal in nature?

A diagnostic treatment trial with antiseizure medication Signup and view all the answers

What signifies that a clinical sign should be considered an electroclinical seizure?

It should be time-locked to the EEG pattern and absent when the pattern is absent. Signup and view all the answers

Why is the term 'nonconvulsive' preferred over 'subclinical'?

It is often unclear if the electrographic activity is contributing to the patient's impaired mental status. Signup and view all the answers

Which features are characteristic of Brief Potentially Ictal Rhythmic Discharges (BIRDs)?

They last less than 10 seconds and consist of at least six waves. Signup and view all the answers

What can be stated about nonconvulsive seizures and electrographic correlates?

Nonconvulsive seizures can exist without a clear electrographic correlate. Signup and view all the answers

What is the necessary condition for a seizure to be categorized as nonconvulsive?

The seizure must not have any motor activity. Signup and view all the answers

Which characteristic defines evolving BIRDs?

They evolve radiatively over the course of the discharge. Signup and view all the answers

What is necessary for a clinical sign to warrant an 'SI-' prefix?

It should be reproducibly related to an alerting stimulus. Signup and view all the answers

Which statement accurately describes electroclinical seizures?

They include episodes with evident behavior change. Signup and view all the answers

Which of these describes a feature that is NOT indicative of nonconvulsive seizures?

They exhibit prominent motor activity. Signup and view all the answers

What can be inferred about BIRDs with similar morphology to seizures?

They are considered definitive BIRDs. Signup and view all the answers

What duration qualifies a waveform as sharp in EEG analysis?

70 to 200 ms Signup and view all the answers

Which term is used to describe waveforms with a steep slope and pointy morphology?

Sharp Signup and view all the answers

How many unequivocal changes are necessary to classify a waveform as evolving?

Two Signup and view all the answers

What characteristic defines a blunt waveform in EEG morphology?

Smooth or sinusoidal morphology Signup and view all the answers

Which category does NOT fall under the definition of SIRPIDs?

Continuous activity Signup and view all the answers

What is the minimum duration required for a pattern to qualify as rhythmic or periodic?

At least 6 consecutive cycles Signup and view all the answers

When patterns qualify as both PDs and RDA, how should they be coded?

As PDs1R and RDA1S Signup and view all the answers

What is the defining frequency relationship described between spike-and-wave complexes?

There is a consistent relationship without gaps Signup and view all the answers

Which duration range qualifies a pattern as 'long'?

10 to 59 minutes Signup and view all the answers

If a rhythmic pattern occurs at 3 Hz for 2 seconds, how is it classified?

It qualifies as PDs Signup and view all the answers

What is defined as Electrographic Status Epilepticus (ESE)?

An electrographic seizure lasting for at least 10 continuous minutes. Signup and view all the answers

Which of the following best describes the duration of an electrographic seizure?

It is defined as lasting 10 seconds or longer. Signup and view all the answers

What is a crucial aspect of the proposed '10 second rule' in defining seizures?

Its elimination sparked significant controversy among authors. Signup and view all the answers

What defines the 20% cutoff for electrographic seizures as stated in the guidelines?

It reflects expert consensus lowering the previous 50% standard. Signup and view all the answers

What is a characteristic identified in electrographic seizures, according to the definitions provided?

Electrographic seizures can include non-epileptiform discharges. Signup and view all the answers

Which statement accurately captures the implications of the International League Against Epilepsy's definitions?

There was significant debate before accepting the '10 second rule.' Signup and view all the answers

What does an electrographic seizure require in terms of discharge frequency?

It needs a minimum of 2.5 Hz for a minimum of 10 seconds. Signup and view all the answers

What was the rationale for the upward adjustment of the percentage cutoff from 50% to 20%?

Based on expert surveys that indicated a lesser risk of neurological decline. Signup and view all the answers

Which characteristic is emphasized for defining evolving patterns in seizures?

There should be sequences that clearly indicate changes over time. Signup and view all the answers

In the classification of electrographic seizures, how is 'sharply contoured' discharge defined?

Discharges that may not necessarily be epileptiform in nature. Signup and view all the answers

Study Notes

Signal Baseline and Phases

The number of phases in a signal is determined by baseline crossings.
Each phase is defined by the signal's position relative to an imaginary baseline.
For example, a signal with two baseline crossings contains three distinct phases (1 pink, 1 blue, 1 yellow).

Phase Sharpness and Type of Stimuli

Sharpness must be specified for both the dominant phase (highest voltage) and the sharpest phase, if different.
Clinical scenarios categorize responses to various stimuli: auditory, light, tactile, non-noxious, and noxious stimuli.

Electrographic Seizures (ESz)

Defined based on Salzburg criteria; can be stimulus-induced.
A clinician must find a clear clinical correlate for the seizure, which should be time-locked to the EEG pattern.

Brief Potentially Ictal Rhythmic Discharges (BIRDs)

Defined as focal or generalized rhythmic patterns lasting 0.5 to less than 10 seconds.
BIRDs should have a regular rate (≥ 4 Hz for at least six waves) and lack a clear clinical correlate.
Paroxysmal fast activity lasting similar time constraints also qualifies as BIRDs.

Ictal-Interictal Continuum (IIC)

Refers to patterns possibly indicating an electrographic seizure, needing careful clinical interpretation.
Not a diagnosis, but signals patterns that might account for the patient's impairments.

Other Terminology and Characteristics

"Triphasic morphology" signifies three phases: negative-positive-negative.
Anterior-posterior lag indicates delays of over 100 ms between anterior and posterior derivations.
Certain patterns associated with increased sharpness, higher amplitude, and fluctuation are deemed more "ictal-appearing."

Classification by Polarity

Polarity of the dominant phase should be described as positive, negative, or unclear, especially in referential montages.
Specify features like dipole or tangential aspects where applicable.

Clinical Correlates and Diagnosis

Expressions like “nonconvulsive” can relate to both electrographic and electroclinical seizures, emphasizing the lack of motor activity.
Potentially ictal discharges could necessitate diagnostic treatment, generally involving antiseizure medications.

EEG Terminology and Definitions

SIRPIDs: Refers to stimulus-induced rhythmic, periodic, or ictal-appearing discharges inclusive of all SI patterns like SI-RDA, SI-PDs, SI-SW, SI-IIC, SI-BIRDs, or SI-seizures.
Waveform Classification:
- Spiky: duration < 70 ms.
- Sharp: duration between 70 to 200 ms.
- Sharply contoured: characterized by steep slope and pointy morphology but long-duration, > 200 ms.
- Blunt: smooth or sinusoidal morphology.

Evolution and Duration of Discharges

Evolution: At least two sequential changes in frequency, morphology, or location.
Duration Classification:
- Very long: ≥ 1 hour.
- Long: 10 to 59 minutes.
- Intermediate: 1 to 9.9 minutes.
- Brief: 10 to 59 seconds.
- Very brief: < 10 seconds.

Electrographic Seizures (ESz) and Status Epilepticus (ESE)

Electrographic Seizures: Defined as patterns with deﬁnite evolution lasting ≥ 10 seconds, with a frequency averaging ≥ 2.5 Hz.
Electrographic Status Epilepticus (ESE): ESz lasting ≥ 10 continuous minutes or comprising > 20% of any 60-minute recording.
Clinical Correlates:
- Definite clinical correlate must be time-locked to seizure patterns.
- Improvement after parenteral antiseizure medication indicates ESE or ECSz.

Electroclinical Seizures (ECSz) and Context

ECSz: Can last <10 seconds if accompanied by a definite clinical correlate.
Requires Monitoring: All EEG data should be evaluated in clinical and paraclinical contexts (history, exams, imaging) to support or invalidate status epilepticus diagnosis.

Patterns and Further Classifications

Evolving patterns (e.g., "evolving RDA") can emerge from electrographic activity evaluated over time.
Lateralized RDA averaging ≥ 1 Hz for at least 10 seconds with fluctuation qualifies for monitoring but does not meet ESz or ESE criteria.

Treatment Protocols

Effective treatment with parenteral antiseizure medication leading to EEG and clinical improvement qualifies as ECSz or ECSE.
If treatment impacts EEG without clinical improvement, it may suggest possible ECSE.
IIC patterns may be influenced by stimulus and can be classified with an "SI-" prefix if reproducible by alerting stimuli.

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Description

Explore the nuances of signal baselines and phases in EEG readings. This quiz delves into the classifications of electrographic seizures, including the Salzburg criteria, and discusses clinically relevant stimuli that affect phase sharpness. Test your knowledge on brief potentially ictal rhythmic discharges and their characteristics.