EDT EDT Nerve Conduction Studies Interpretation 2

Question 1

What is the significance of conduction block in a nerve conduction study?

Accepted Answer

It suggests focal demyelination preventing impulse propagation across a segment

Answer

Conduction block is caused by focal demyelination that prevents action potential propagation, resulting in CMAP amplitude drop of ≥50% across a nerve segment.

Question 2

F-wave studies are used primarily to evaluate:

Accepted Answer

Proximal motor nerve and root conduction

Answer

F-waves travel antidromically to motor neurons and orthodromically back to the muscle, allowing evaluation of proximal motor nerve and spinal root integrity.

Question 3

When is the H-reflex most clinically useful in EDX testing?

Accepted Answer

Evaluating S1 radiculopathy

Answer

The H-reflex evaluates the S1 reflex arc (tibial nerve, S1 root, gastrocnemius/soleus), making it the most sensitive NCS measure for S1 radiculopathy.

Question 4

In a patient with polyneuropathy, which pattern of NCS abnormalities suggests primary demyelination?

Accepted Answer

Uniform slowing of conduction velocities with prolonged distal latencies

Answer

Primary demyelinating polyneuropathy shows uniform slowing of conduction velocities and prolonged distal latencies, reflecting widespread myelin damage.

Question 5

The normal range for median motor distal latency in adults is approximately:

Accepted Answer

2–4 ms

Answer

Median motor distal latency is normally 2–4 ms; values above 4.4 ms are generally considered abnormal for carpal tunnel syndrome evaluation.

(EDT) Electrodiagnostic Technician Certification Practice Test

(EDT) Electrodiagnostic Technician Certification Practice Test

EDT EDT Nerve Conduction Studies Interpretation 2