HICU - Background Activity

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Questions and Answers

In the context of critical care EEG, what distinguishes 'mildly asymmetric' EEG background activity from 'markedly asymmetric' activity?

Mild asymmetry refers to frequency differences exceeding 2 Hz, whereas marked asymmetry manifests as burst suppression patterns.
Mild asymmetry involves amplitude differences exceeding 75% on referential recording, while marked asymmetry is defined by the presence of epileptiform discharges.
Mild asymmetry corresponds to voltage attenuation of less than 20 µV, and marked asymmetry corresponds to complete voltage suppression in one hemisphere.
Mild asymmetry is indicated by amplitude asymmetry less than 50% or frequency asymmetry of 0.5–1 Hz, while marked asymmetry shows amplitude asymmetry ≥50% or frequency asymmetry >1 Hz. (correct)

How does the presence of 'attenuation' in EEG recordings relate to the assessment of 'continuity' in background activity?

Nearly continuous activity involves occasional attenuation or suppression (<10% of the record), while discontinuous activity refers to attenuation or suppression in 10–49% of the record. (correct)
Attenuation indicates the presence of epileptiform activity, which is unrelated to continuity.
Attenuation is irrelevant to continuity, as it only reflects changes in amplitude.
Continuity is disrupted by sleep transients; attenuation determines if those are normal or abnormal.

What is the specific clinical significance of documenting sedating medications in the context of EEG background activity interpretation in critically ill patients?

Documentation is only relevant for neuromuscular blocking agents, as these directly affect EEG waveforms.
Sedative medications have no impact on EEG background activity and do not need to be documented.
Sedating medications, especially IV anesthetics, can profoundly alter EEG patterns, and their potential contribution to background slowing must be considered to avoid misinterpreting the severity of cerebral dysfunction. (correct)
Documentation is only needed if the patient experiences paradoxical reactions to sedatives, such as increased agitation.

In the context of EEG reactivity assessment in comatose patients, how should stimulation be escalated if initial auditory stimuli do not elicit a response?

Progress to somatosensory and/or noxious stimuli such as sternal rub or nasal tickle after auditory stimuli fail to elicit a response. (A) Signup and view all the answers

What is the electrophysiological criterion for defining electrocerebral inactivity (ECI), and under what specific conditions is this criterion considered valid for determining brain death?

ECI is defined as the absence of EEG activity greater than 2 µV, and is indicative of brain death only when appropriate technical standards are met, including normothermia and absence of sedative medications. (D) Signup and view all the answers

How do anesthetic agents like propofol, pentobarbital, and midazolam confound the assessment of sleep patterns in encephalopathic patients, and what specific EEG features are most affected?

Anesthetic agents induce sleep-like states marked by the emergence of K-complexes and spindles, complicating the interpretation of genuine sleep architecture. (C) Signup and view all the answers

In EEG interpretation, what is the physiological basis for measuring voltage fields, and what specific neuronal structure is primarily responsible for generating these fields during scalp EEG recordings?

Scalp EEG measures voltage fields produced by cortical pyramidal neuron generators with an electrical field component perpendicular to the scalp recording site. (D) Signup and view all the answers

What are the limitations of relying solely on EEG background activity for determining the etiology of cerebral dysfunction in critically ill patients?

EEG background activity, while informative about global cerebral function and prognosis, is often nonspecific regarding the underlying etiology. (D) Signup and view all the answers

In the context of EEG interpretation, how does the concept of 'bistability' relate to endogenous arousal systems, and what are the implications for state transitions in encephalopathic patients?

Bistability indicates that arousal systems intrinsically jump between asleep and awake states without a clear intermediate pattern, potentially manifesting as abrupt state transitions in encephalopathic patients. (A) Signup and view all the answers

Which of the following statements best describes the clinical utility of continuous EEG (cEEG) monitoring in the intensive care unit (ICU) for assessing changes in background activity over time?

cEEG allows for the assessment of changes in background activity over time, potentially revealing a trajectory of improvement or worsening that can guide clinical management. (B) Signup and view all the answers

When EEG reactivity is assessed, what feature is universally accepted, and what change (if any) should be noted?

Any correlated change in cerebral activity should be accepted. (D) Signup and view all the answers

In patients with traumatic brain injury, how does EEG reactivity correlate with a good long-term global nurological recovery?

EEG reactivity after 24 hours is highly predictive. (D) Signup and view all the answers

Regarding alpha and spindle coma EEG patterns, what prognostic factor indicates a positive sign for recovery?

Preserved background reactivity to stimuli. (B) Signup and view all the answers

What factor may be important in prediction of prognosis in patients who undewent targete temperature mangaement after cardiac arrest?

Reactivity (A) Signup and view all the answers

What EEG sleep elements are important in evaluating encephalopathy?

Presence or absence of both sleep spindles and K-complexes should be recorded. (A) Signup and view all the answers

What is identified as a positive prognostic sign in patients with non-hypoxic-ischemic encephalopathy?

Preservation of K-complexes. (A) Signup and view all the answers

In patients with continuous EEG after status epilepticus, the presence of what patters correlates with complete recovery?

Stage II sleep patterns. (C) Signup and view all the answers

Altered sleep states play a role in what activity that appear to be state transitions?

Cyclic alternating patterns (D) Signup and view all the answers

What EEG patterns could help differentiate between different etiologies of encephalopathy and coma?

Quantitative EEG (C) Signup and view all the answers

Diffuse polymorphic delta activity is most often caused by what type of abnormalitiy?

Structural abnormalities involving subcortical white matter (B) Signup and view all the answers

What does generalized suppression indicate?

Profound cerebral dysfucntion (B) Signup and view all the answers

How should stimulation for reactivity testing be graded?

Start with audiotory stimulation, then somatosensory or noxious stimulation. (B) Signup and view all the answers

Normal EEG amplitude ranges between what?

20 to 200 µV (C) Signup and view all the answers

What must EEG recordings demonstrate to reach brain death?

EEG recordings must demonstrate electrocerebral inactivity. There cannot be any observed rhythm. This must be determined absent sedatives with normal therma control. (C) Signup and view all the answers

How can the severity of generalized cerebral dysfunction in critically ill patients be classified according to EEG changes?

Mild, moderate, severe, and profound (C) Signup and view all the answers

How should attenuation of an EEG in regards to background amplitude be described?

Attenuation defined as more than 10 µV, and less than 50% of background amplitude (B) Signup and view all the answers

In cat studies, what structures were found to be needed for the EEG reactivity?

Both A and B (A) Signup and view all the answers

How often should EEG background reactivity be assessed in every ICU EEG?

Once every 24 hours (B) Signup and view all the answers

What EEG characteristic helps to differentiate between normal or abnormal?

Sleep transients (A) Signup and view all the answers

What is the definition of suppression regarding background amplitude?

All activity <10 µV (A) Signup and view all the answers

What is the voltage range in Longitudinal Bipolar (LB) that is regarded as normal, low and suppressed activity?

normal is more than 20 microvolts, low is less than 20 microvolts and supressed is less than 10 microvolts (C) Signup and view all the answers

Continuity is a term, what does nearly continous mean the context of EEG monitoring?

Nearly continous means occasional periods of attenuation or suppression less than 10 (C) Signup and view all the answers

Which of the background frequencies are mostly documentented?

Delta, Theta and Alpha (C) Signup and view all the answers

What are Key points needed for EEG intrpretation?

Standardized terminology (B) Signup and view all the answers

Why is EEG Background activity important?

EEG Background activity provides real-time window to monitor change in global cerebral function. (D) Signup and view all the answers

How should EEG Background be compared?

EEG background is compared in left and right hemispheres and is defined by Symmetric, Mildly Asymmetric, or Markedly Asymmetric. (A) Signup and view all the answers

Flashcards

Importance of EEG background activity

EEG background activity provides a real-time window to monitor changes in global cerebral function, though often nonspecific for etiology.

EEG hemisphere symmetry

Compare EEG activity between hemispheres, identifying as symmetric, mildly asymmetric, or markedly asymmetric based on amplitude/frequency differences.