EEG Artifact Identification 4 — Questions and Answers
Question 1: A rhythmic artifact at exactly 60 Hz appearing uniformly across all electrodes is most consistent with:
- Muscle artifact
- AC line noise (Correct answer)
- Electrode pop
- Cardiac artifact
Correct answer: AC line noise
60 Hz AC line noise appears as a uniform, rhythmic interference at power line frequency across all or many electrodes.
Question 2: Which artifact would most likely appear as a high-amplitude, low-frequency deflection time-locked to the R-wave on ECG?
- Sweat artifact
- Pulse artifact (Correct answer)
- Chewing artifact
- Electrode pop
Correct answer: Pulse artifact
Pulse artifact is caused by scalp vessel pulsations under electrodes and appears as slow deflections synchronous with the cardiac cycle.
Question 3: A technologist notices intermittent square-wave transients isolated to a single electrode that disappear when the electrode impedance is rechecked and re-gelled. This is most consistent with:
- Muscle artifact
- Electrode pop (Correct answer)
- Sweat artifact
- EKG artifact
Correct answer: Electrode pop
Electrode pops are caused by intermittent loss of contact or impedance instability at a single electrode and typically resolve with re-application.
Question 4: Slow, sinusoidal, high-amplitude waves that wax and wane over frontal electrodes in a drowsy, diaphoretic patient are most characteristic of:
- Delta slowing
- Sweat artifact (Correct answer)
- Eye movement artifact
- Muscle artifact
Correct answer: Sweat artifact
Sweat artifact produces slow (< 1 Hz), large-amplitude sinusoidal waves predominantly over frontal regions due to sweat gland activity.
Question 5: An artifact appearing as a rhythmic, 1–3 Hz broad, high-amplitude slow-wave pattern that correlates with the patient's assisted ventilation rate is called:
- Tremor artifact
- Ventilator artifact (Correct answer)
- Cardiac artifact
- Movement artifact
Correct answer: Ventilator artifact
Ventilator artifact is caused by rhythmic chest and head movement from mechanical ventilation, producing slow waves at the ventilation rate.
Question 6: In a referential montage, an artifact that appears identical in amplitude and polarity on ALL channels simultaneously most likely originates from:
- A single scalp electrode
- The reference electrode (Correct answer)
- Muscle activity
- Eye blinks
Correct answer: The reference electrode
When artifact appears on all channels equally in a referential montage, it is localized to the common reference electrode, not the active electrodes.
Question 7: High-frequency, irregular bursts of activity seen maximally over temporal and frontal electrodes during a patient interview are most consistent with:
- Temporal lobe seizure
- Chewing/jaw muscle artifact (Correct answer)
- Electrode noise
- Cardiac artifact
Correct answer: Chewing/jaw muscle artifact
Chewing produces high-frequency myogenic artifact maximal over temporal regions due to masseter and temporalis muscle proximity.
EEG Artifact Identification 4
A rhythmic artifact at exactly 60 Hz appearing uniformly across all electrodes is most consistent with: