Podcast
Questions and Answers
What does electrocerebral inactivity typically indicate?
What does electrocerebral inactivity typically indicate?
SIRPIDs are associated with better outcomes in patients with severe brain injuries.
SIRPIDs are associated with better outcomes in patients with severe brain injuries.
False
What does ELAEs stand for in EEG findings?
What does ELAEs stand for in EEG findings?
Episodic Low-Amplitude Events
The phenomenon characterized by an alternation of periods of attenuation and bursts of EEG activity is known as __________.
The phenomenon characterized by an alternation of periods of attenuation and bursts of EEG activity is known as __________.
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Match the following EEG patterns with their descriptions:
Match the following EEG patterns with their descriptions:
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Which of the following EEG patterns is associated with seizures?
Which of the following EEG patterns is associated with seizures?
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Stimulus-induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDs) can regress with parenteral lorazepam.
Stimulus-induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDs) can regress with parenteral lorazepam.
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What type of EEG pattern is characterized by triphasic morphology?
What type of EEG pattern is characterized by triphasic morphology?
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What are diffuse non-specific EEG slowings associated with?
What are diffuse non-specific EEG slowings associated with?
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________ discharges are found to be frequency-dependent indicators of brain tissue hypoxia.
________ discharges are found to be frequency-dependent indicators of brain tissue hypoxia.
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Focal EEG slowings are exclusively linked to metabolic disorders.
Focal EEG slowings are exclusively linked to metabolic disorders.
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What may hypersynchronous diffuse slowings indicate?
What may hypersynchronous diffuse slowings indicate?
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Match the following EEG patterns with their clinical significance:
Match the following EEG patterns with their clinical significance:
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Which EEG pattern is often used to stratify risk in the interictal and ictal continuum?
Which EEG pattern is often used to stratify risk in the interictal and ictal continuum?
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EEG slowings that are focal are connected with ________ brain lesions.
EEG slowings that are focal are connected with ________ brain lesions.
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Match the EEG findings with their associated conditions:
Match the EEG findings with their associated conditions:
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All generalized periodic discharges have triphasic morphology.
All generalized periodic discharges have triphasic morphology.
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What is the significance of OIRDA in pediatric patients?
What is the significance of OIRDA in pediatric patients?
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What is a significant characteristic of focal EEG slowings?
What is a significant characteristic of focal EEG slowings?
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What is one major limitation of EEG regarding brain lesions?
What is one major limitation of EEG regarding brain lesions?
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The terminology used to describe epileptiform abnormalities is consistently agreed upon among electroencephalographers.
The terminology used to describe epileptiform abnormalities is consistently agreed upon among electroencephalographers.
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Study Notes
Pathological EEG Patterns
- This study module discusses pathological EEG patterns.
- The author is Oriano Mecarelli, from the Department of Human Neurosciences, Sapienza University of Rome, Italy.
- The text is based on a study published by Mecarelli in 2019.
Changes in Background Rhythms
- Background EEG abnormalities can include amplitude reduction or poor synchronization of physiological rhythms.
- Unilateral or bilateral slowings in background EEG are also considered.
- Reduced or absent response to eye opening and alerting are important factors.
- Many healthy individuals have naturally low-amplitude EEG, related to anxiety or non-relaxing environments.
- Asymmetry in posterior alpha rhythm amplitude (less voltage over the dominant hemisphere) is normal but not when the difference exceeds 50% compared to the contralateral side.
- Unilateral attenuation or absence of the alpha rhythm often indicates lesions in the occipital cortex or anterior ventral thalamus; posterior subcortical lesions can also cause lack of alpha reactivity to eye opening.
EEG Slowings
- EEG slowings encompass activities with frequencies below the alpha band (e.g., theta, delta).
- Slow-wave abnormalities can be focal or diffuse, and involve morphology (mono- or polymorphic), rhythmicity (irregular vs rhythmic), and amplitude (low or high voltage).
- Continuity (intermittent/subcontinuous vs continuous) is also important.
- Diffuse slowings are common in various conditions (e.g., consciousness disorders, cerebral inflammation, neurodegenerative processes).
- Severity of underlying pathology can be inferred from extent and reactivity of slowings.
- Hypersynchronous diffuse slowings can be caused by drowsiness or hyperventilation and don't necessarily indicate pathology.
- Focal slowings are strongly related to structural brain lesions (tumors, hematoma, stroke).
- The features of the slowing sequence (frequency, duration, morphology, amplitude) provide crucial clinical information.
- EEG slow changes from structural brain lesions reflect cortical function dysfunction.
- EEG is not useful for distinguishing various types of brain lesions.
- Slowing tends to appear periodically or rhythmically.
Epileptiform Abnormalities
- There's still confusion on the definition of epileptic abnormalities among electroencephalographers.
- Terms like "discharge," "interictal," "ictal," and "subclinical" are not always interpreted identically.
- Some electroencephalographers use the term "irritative", correlated with epilepsy but discouraged nowadays.
- The revised glossary of the IFCN (2017) focuses on the morphology of EEG graphoelements without considering clinical aspects.
Periodic Patterns
- Periodic patterns in EEG are defined as waves or complexes occurring regularly or intermittently, at nearly regular intervals.
- "Quasi-periodic" patterns are used to describe events not truly periodic because of variations.
- The intervals must be determined quantitatively.
- Periodic discharges (PDs) have a repetitive, uniformly morphologic waveform with a quantifiable interval.
- Several classes of PDs can be distinguished, with classifications evolving based on older terminology and more recent standards.
Attenuation/Suppression and Electrocerebral Inactivity
- EEG attenuation, suppression, or total loss of activity may result from reduced cortical activity, caused by reversible or irreversible brain injuries.
- The severity and duration vary, until reaching electrocerebral inactivity (brain death).
Rhythmic Patterns
- Rhythmic patterns refer to regular waveforms with a consistent period and relative uniformity.
- Rhythmic Delta Activity (RDA) involves a repeated sequence of waves below 4 Hz without interval between waves.
- Intermittent Rhythmic Delta Activity (IRDA) shows similar waves that are burst-like and occur with intervals between bursts.
- Frontal Intermittent Rhythmic Delta Activity (FIRDA) is a type of IRDA specifically characterized by bursts of waves at 1.5-2.5 Hz predominantly in frontal areas.
- Occipital Intermittent Rhythmic Delta Activity (OIRDA) are similar bursts of waves at 2-3 Hz localized in the occipital areas.
Stimulus-Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDs)
- SIRPIDs are elicited by stimulation, such as auditory, sensory, or noxious stimuli.
- The relation between SIRPIDs and clinical seizures is not always clear, and sometimes not directly correlated.
Other Relevant Topics
- Different types of EEG patterns are described along with their characteristics, and examples of each are illustrated visually.
- The interpretation of EEG is subjective and influenced by the technician's/neurophysiologist's expertise and the patient's condition.
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Description
Test your knowledge on EEG findings and their implications. This quiz covers topics such as electrocerebral inactivity, SIRPIDs, and the alternation of EEG activity patterns. Engage with matching tasks and improve your understanding of clinical neurophysiology.
