Non-Epileptiform Abnormalities Flashcards

Which non-epileptiform EEG pattern is characterized by high-voltage, chaotic slow and sharp waves without organized background activity, classically seen in infantile spasms?

Answer: Hypsarrhythmia

Hypsarrhythmia is the interictal EEG hallmark of West syndrome (infantile spasms), featuring high-amplitude disorganized slow activity with multifocal spikes.

Generalized rhythmic delta activity (GRDA) persisting despite stimulation is most suggestive of which condition compared to GRDA that attenuates with stimulation?

Answer: GRDA that persists is more likely ictal; GRDA that attenuates is more likely non-ictal

GRDA that does not attenuate with stimulation (non-reactive) raises concern for ictal or peri-ictal activity, while stimulus-induced attenuation suggests non-epileptiform encephalopathy.

Which medication commonly produces diffuse beta activity as a non-epileptiform EEG abnormality?

Answer: Benzodiazepines

Benzodiazepines and barbiturates classically increase diffuse beta activity (>13 Hz), which is a drug effect rather than a pathological finding.

An EEG showing continuous generalized polymorphic delta slowing with no clear faster frequencies in a patient with altered consciousness most likely indicates what?

Answer: Severe diffuse cortical dysfunction

Continuous generalized polymorphic delta without faster activity in a wakeful patient indicates severe diffuse encephalopathy affecting cortical function.

TIRDA (Temporal Intermittent Rhythmic Delta Activity) is considered a non-epileptiform abnormality but is clinically significant because it is associated with which condition?

Answer: Temporal lobe epilepsy

TIRDA, while not epileptiform itself, is strongly associated with temporal lobe epilepsy and should prompt clinical correlation for seizure disorder.

Which EEG feature differentiates true electrocerebral inactivity from a technical artifact producing an isoelectric-appearing record?

Answer: Increasing interelectrode distances, confirming low impedances, and testing reactivity with painful stimuli

Confirming ECI requires technical verification including electrode impedances <10 kΩ, interelectrode distance ≥10 cm, high sensitivity settings, and absence of reactivity to stimulation.

A patient with uremic encephalopathy undergoes EEG. Which pattern would be an expected non-epileptiform abnormality in this setting?

Answer: Diffuse theta-delta slowing with possible triphasic waves

Uremic encephalopathy typically produces diffuse background slowing into the theta and delta ranges, sometimes with triphasic morphology similar to hepatic encephalopathy.