EDT EDT Quality Assurance & Documentation 1 — Questions and Answers
Question 1: When documenting nerve conduction study results, which parameter is most critical to report for evaluating axonal integrity?
- Conduction velocity only
- Peak latency and amplitude together
- Amplitude of the evoked potential (Correct answer)
- Skin temperature at the time of testing
Correct answer: Amplitude of the evoked potential
Amplitude of the evoked potential (CMAP or SNAP) directly reflects the number of functioning axons and is the critical parameter for assessing axonal integrity.
Question 2: Temperature correction in nerve conduction studies is important because:
- Warmer limbs produce lower amplitude potentials
- Cooler temperatures slow conduction velocity and prolong latencies, potentially mimicking neuropathy (Correct answer)
- Temperature does not affect NCS parameters
- Warmer temperatures cause conduction block
Correct answer: Cooler temperatures slow conduction velocity and prolong latencies, potentially mimicking neuropathy
Limb cooling slows ion channel kinetics, increasing latencies and slowing conduction velocity, which can produce false-positive findings if not recognized and corrected.
Question 3: The minimum skin temperature recommended for routine nerve conduction studies in the upper extremity is:
- 25°C
- 32°C (Correct answer)
- 37°C
- 20°C
Correct answer: 32°C
The minimum recommended skin temperature for upper extremity NCS is 32°C (with lower extremity at 30°C) to ensure accurate conduction velocity measurements.
Question 4: In an EDX report, it is important to include which of the following to ensure reproducibility?
- Patient's insurance information
- Electrode placement sites, distances measured, filter settings, and sweep speeds used (Correct answer)
- The technician's personal interpretation of the findings
- Only the numerical values without reference ranges
Correct answer: Electrode placement sites, distances measured, filter settings, and sweep speeds used
Documenting electrode placement, measured distances, filter settings, and sweep speeds allows reproducibility and meaningful comparison with future studies.
Question 5: What is the standard interelectrode distance recommended for recording the median motor CMAP from the abductor pollicis brevis (APB)?
- 1 cm
- 3 cm (Correct answer)
- 8 cm
- Distance is not standardized for this study
Correct answer: 3 cm
The active electrode is placed over the APB muscle belly and the reference electrode approximately 3–4 cm distally at the proximal thumb IP joint, ensuring consistent and reproducible recordings.
Question 6: Which of the following is a common technical artifact that can falsely prolong distal latency in motor NCS?
- High filter settings
- Recording electrode placement over the tendon rather than the muscle belly (Correct answer)
- Increasing stimulus duration
- Using a low-impedance ground electrode
Correct answer: Recording electrode placement over the tendon rather than the muscle belly
Placing the active electrode over the tendon instead of the muscle belly produces a volume-conducted response with apparent latency prolongation and altered waveform morphology.
EDT EDT Quality Assurance & Documentation 1
When documenting nerve conduction study results, which parameter is most critical to report for evaluating axonal integrity?