EMG Nerve Conduction Studies 3

Question 1

In a preganglionic nerve root avulsion (proximal to the dorsal root ganglion), what is the expected sensory NCS finding in the affected territory?

Accepted Answer

Normal or preserved SNAP despite clinical sensory loss

Answer

Absent SNAP due to Wallerian degeneration of peripheral axons

Answer

Reduced SNAP proportional to clinical sensory deficits

Answer

Increased SNAP amplitude due to collateral sprouting

Question 2

For reliable across-elbow ulnar nerve conduction velocity measurement, the minimum recommended distance between below-elbow and above-elbow stimulation points is:

Accepted Answer

10 cm

Answer

5 cm

Answer

20 cm

Answer

30 cm

Question 3

Recording the CMAP from the abductor digiti minimi (ADM) is used to evaluate which nerve?

Accepted Answer

Ulnar nerve

Answer

Median nerve

Answer

Radial nerve

Answer

Anterior interosseous nerve

Question 4

In peroneal nerve palsy at the fibular head, which NCS finding best distinguishes focal demyelination from axonal loss at that site?

Accepted Answer

Conduction block or focal velocity slowing across the fibular head segment

Answer

Reduced CMAP amplitude with both distal and proximal stimulation equally

Answer

Absent sural nerve SNAP amplitude

Answer

Prolonged H-reflex latency

Question 5

The minimum number of F-wave trials recommended per nerve to reliably determine minimum F-wave latency is:

Accepted Answer

10

Answer

5

Answer

20

Answer

30

Question 6

Normal sensory nerve conduction velocity in upper extremity sensory nerves in adults generally exceeds:

Accepted Answer

50 m/s

Answer

30 m/s

Answer

40 m/s

Answer

70 m/s

Question 7

Which electrodiagnostic technique is the most useful for evaluating the S1 nerve root and sacral plexus integrity?

Accepted Answer

Tibial nerve H-reflex

Answer

Median F-wave study

Answer

Peroneal motor nerve conduction study

Answer

Sural sensory nerve conduction study