CNIM Electroencephalography (EEG) in the Operating Room

Question 1

What is the standard electrode placement system used for intraoperative EEG monitoring?

Accepted Answer

10-20 International System

Answer

The 10-20 International System is the universally accepted standard for scalp electrode placement in both routine and intraoperative EEG.

Question 2

Which EEG frequency band is typically dominant during relaxed wakefulness with eyes closed?

Accepted Answer

Alpha (8–13 Hz)

Answer

Alpha rhythm (8–13 Hz) is the dominant posterior rhythm during relaxed wakefulness with eyes closed, and is attenuated by eye opening or mental effort.

Question 3

What type of EEG montage references each electrode to the mathematical average of all scalp electrodes?

Accepted Answer

Common average reference montage

Answer

The common average reference montage subtracts the mean signal of all scalp electrodes from each individual channel, minimizing bias from any single reference site.

Question 4

Which filter setting is MOST appropriate for eliminating 60 Hz power line interference in intraoperative EEG?

Accepted Answer

Notch filter at 60 Hz

Answer

A 60 Hz notch filter selectively removes power line artifact while preserving all clinically relevant EEG frequency bands.

Question 5

What electrode impedance level is considered acceptable for reliable intraoperative EEG recording?

Accepted Answer

Less than 5 kΩ

Answer

Electrode impedances below 5 kΩ ensure good electrical contact, minimizing artifact and maintaining signal integrity in the OR environment.

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM - Certification for Neurophysiological Intraoperative Monitoring Practice Test

CNIM Electroencephalography (EEG) in the Operating Room