EDT Device Setup & Operation 5

Question 1

During setup for intraoperative neurophysiological monitoring using EMG, which mode should the system be set to for detecting spontaneous activity that indicates nerve irritation?

Accepted Answer

Free-run (continuous) EMG mode

Answer

Free-run EMG continuously monitors for spontaneous activity such as neurotonic discharges that signal mechanical nerve irritation during surgery.

Question 2

When the cathode and anode of the stimulating electrode are accidentally reversed during a nerve conduction study, what is the most notable effect?

Accepted Answer

Anodal stimulation creates virtual cathode depolarization at a more proximal site, artificially shortening latency

Answer

When the anode is inadvertently placed distally, hyperpolarization under the anode can cause virtual cathode effects that activate the nerve at a site closer to the recording electrode, falsely shortening the measured latency.

Question 3

For a single-fiber EMG (SFEMG) recording, which needle type and filter settings are required?

Accepted Answer

Single-fiber needle with high-pass filter of 500 Hz

Answer

SFEMG uses a specialized single-fiber needle electrode and a high-pass filter of 500 Hz to isolate action potentials from individual muscle fibers.

Question 4

A technician performing median nerve sensory NCS obtains a SNAP with a normal onset latency but significantly reduced amplitude. Before concluding pathology, which technical factor should be reviewed first?

Accepted Answer

E1 electrode placement accuracy over the nerve

Answer

Misplacement of E1 away from the nerve trunk can attenuate amplitude without affecting latency, mimicking axonal loss.

Question 5

Which of the following correctly describes the purpose of increasing the number of averages in a nerve conduction study?

Accepted Answer

It improves signal-to-noise ratio by reinforcing the time-locked response while averaging out random noise

Answer

Each sweep adds the stimulus-locked response coherently while noise, being random, partially cancels, improving the signal-to-noise ratio by the square root of the number of averages.

(EDT) Electrodiagnostic Technician Certification Practice Test

(EDT) Electrodiagnostic Technician Certification Practice Test

EDT Device Setup & Operation 5