BRPT Scoring Artifacts and Troubleshooting 1 — Questions and Answers
Question 1: A 60 Hz artifact appearing simultaneously on ALL EEG channels most likely indicates a problem with which electrode?
- An active scalp electrode (e.g., C3)
- The ground or reference electrode (Correct answer)
- The chin EMG electrode
- The leg EMG electrode
Correct answer: The ground or reference electrode
When 60 Hz artifact appears on every channel at once, the common element — the ground or reference electrode — is the most likely source rather than individual recording electrodes.
Question 2: ECG (cardiogenic) artifact in EEG channels is identified by:
- Slow undulating baseline drift
- Regular sharp deflections that align with QRS complexes on the ECG channel (Correct answer)
- High-frequency irregular bursts unrelated to heart rate
- A sudden flat isoelectric segment
Correct answer: Regular sharp deflections that align with QRS complexes on the ECG channel
ECG artifact appears as regular spikes in EEG that align precisely with QRS complexes, caused by cardiac electrical activity spreading to scalp electrodes.
Question 3: Sweat artifact in a PSG EEG recording is characterized by:
- High-frequency irregular activity above 100 Hz
- Very slow, large-amplitude undulating baseline shifts below 0.5 Hz (Correct answer)
- Regular 60 Hz sinusoidal waves
- Sudden sharp electrode-pop deflections
Correct answer: Very slow, large-amplitude undulating baseline shifts below 0.5 Hz
Sweat artifact produces very slow, large-amplitude baseline undulations below 0.5 Hz as ionic changes in perspiration alter electrode potential.
Question 4: An electrode pop artifact is best identified by:
- Slow undulating waves on all channels
- Regular 60 Hz sine waves on one channel
- A sudden sharp deflection or step change isolated to a single channel (Correct answer)
- High-frequency muscle activity on all channels
Correct answer: A sudden sharp deflection or step change isolated to a single channel
An electrode pop is caused by a momentary change in electrode impedance, producing a sudden sharp deflection or offset in only the affected single channel.
Question 5: Muscle (EMG) artifact in EEG channels is characterized by:
- Regular 60 Hz sine waves
- High-frequency irregular activity typically above 100 Hz that obscures the EEG signal (Correct answer)
- Slow 0.5–2 Hz waves
- Sharp K-complex-like deflections at irregular intervals
Correct answer: High-frequency irregular activity typically above 100 Hz that obscures the EEG signal
Muscle artifact appears as fast, irregular, high-frequency activity (often >100 Hz) that rides on the EEG, making underlying brain activity difficult to score.
Question 6: When an electrode shows high impedance during PSG, what is the correct first troubleshooting step?
- Replace the entire electrode set
- Re-prep the skin, reapply conductive gel, and re-seat the electrode (Correct answer)
- Increase the amplifier sensitivity setting
- Apply a 60 Hz notch filter
Correct answer: Re-prep the skin, reapply conductive gel, and re-seat the electrode
High impedance most commonly results from inadequate skin preparation or insufficient conductive medium; re-abrading the skin and reapplying gel usually resolves it.
BRPT Scoring Artifacts and Troubleshooting 1
A 60 Hz artifact appearing simultaneously on ALL EEG channels most likely indicates a problem with which electrode?