EDT Device Setup & Operation 4

Question 1

A technician is setting up for a sural nerve SNAP and the signal appears noisy even after improving electrode contact. Which additional step is most appropriate?

Accepted Answer

Use signal averaging to extract the low-amplitude SNAP from noise

Answer

Signal averaging sums repeated responses, increasing the signal-to-noise ratio, which is especially useful for low-amplitude sensory potentials.

Question 2

What is the effect of a low skin temperature on nerve conduction velocity measurements?

Accepted Answer

Velocity decreases and latencies prolong

Answer

Cold temperatures slow ion channel kinetics, reducing conduction velocity and prolonging latencies by approximately 1–2 m/s per degree Celsius.

Question 3

When setting up for a blink reflex study, where should the active (E1) recording electrode be placed?

Accepted Answer

Below the eye, over the orbicularis oculi muscle

Answer

The orbicularis oculi is the target muscle for blink reflex recordings; E1 is placed infraorbitally beneath the eye.

Question 4

Which ground electrode placement is preferred during lower extremity nerve conduction studies to minimize stimulus artifact?

Accepted Answer

Between the stimulating and recording electrodes on the same limb

Answer

Placing the ground between the stimulator and recording electrodes intercepts and dissipates stimulus artifact before it reaches the recording site.

Question 5

An EMG machine displays 'impedance mismatch' between E1 and E2. Which of the following is the most likely consequence if recording proceeds without correction?

Accepted Answer

Increased common-mode noise and degraded signal quality

Answer

Unequal electrode impedances degrade the differential amplifier's common-mode rejection, allowing more noise into the recording.

(EDT) Electrodiagnostic Technician Certification Practice Test

(EDT) Electrodiagnostic Technician Certification Practice Test

EDT Device Setup & Operation 4