EEG ICU and Continuous EEG Monitoring 2 — Questions and Answers
Question 1: Generalized periodic discharges (GPDs) are most classically associated with which condition?
- Creutzfeldt-Jakob disease (CJD) (Correct answer)
- Herpes simplex encephalitis
- Acute ischemic stroke
- Hypoxic-ischemic encephalopathy
Correct answer: Creutzfeldt-Jakob disease (CJD)
GPDs (formerly called generalized PLEDs or BiPLEDs) with a triphasic morphology are classically associated with CJD, though they also appear in metabolic encephalopathies.
Question 2: Triphasic waves on EEG in an ICU patient most commonly indicate:
- Toxic-metabolic encephalopathy such as hepatic or uremic encephalopathy (Correct answer)
- Active convulsive seizure
- Stage N3 sleep
- Focal structural lesion
Correct answer: Toxic-metabolic encephalopathy such as hepatic or uremic encephalopathy
Triphasic waves — broad, anteriorly dominant GPDs with three phases — are a classic EEG marker of metabolic encephalopathy, particularly hepatic or uremic encephalopathy.
Question 3: Electrocerebral silence (ECS) on EEG, required for brain death determination, must be recorded at a sensitivity of:
- 2 µV/mm for 30 minutes with inter-electrode distances ≥10 cm (Correct answer)
- 5 µV/mm for 15 minutes
- 10 µV/mm for 60 minutes
- 1 µV/mm for 10 minutes
Correct answer: 2 µV/mm for 30 minutes with inter-electrode distances ≥10 cm
ACNS guidelines for EEG confirmation of brain death require recording at ≥2 µV/mm sensitivity for at least 30 minutes, using electrodes ≥10 cm apart, with no reactivity.
Question 4: In the ACNS ICU EEG terminology, the '+F' modifier on a periodic discharge pattern indicates:
- Superimposed fast activity on the discharge (Correct answer)
- Focal predominance of the pattern
- Associated frequency >4 Hz
- Fixed morphology unchanged over time
Correct answer: Superimposed fast activity on the discharge
The '+F' modifier in ACNS standardized terminology denotes the presence of superimposed fast (beta-range) activity riding on top of the periodic or rhythmic discharge.
Question 5: A cEEG monitoring technologist notices sudden onset of rhythmic, evolving 2 Hz sharp-wave activity for 90 seconds followed by postictal slowing. This is best classified as:
- Electrographic seizure (Correct answer)
- Lateralized periodic discharge
- Rhythmic delta activity
- Breach rhythm
Correct answer: Electrographic seizure
An electrographic seizure requires evolution in frequency, morphology, or spatial distribution lasting ≥10 seconds, and this pattern with evolution and postictal slowing meets criteria.
Question 6: Which EEG background feature in a comatose patient after cardiac arrest is associated with the BEST neurological prognosis?
- Continuous background with preserved reactivity (Correct answer)
- Burst suppression with identical bursts
- Electrocerebral silence
- Generalized suppression <10 µV
Correct answer: Continuous background with preserved reactivity
A continuous EEG background with preserved reactivity to stimulation is the most favorable prognostic finding in post-cardiac arrest coma, suggesting intact cortical function.
EEG ICU and Continuous EEG Monitoring 2
Generalized periodic discharges (GPDs) are most classically associated with which condition?