EDT EDT Clinical Correlations & Pathology 2

Question 1

In suspected myasthenia gravis, what is the most sensitive EDX test?

Accepted Answer

Single-fiber EMG (SFEMG)

Answer

Single-fiber EMG, which measures jitter (variability in fiber discharge timing within a motor unit), is the most sensitive EDX test for neuromuscular junction disease including myasthenia gravis.

Question 2

Chronic inflammatory demyelinating polyneuropathy (CIDP) is differentiated from Charcot-Marie-Tooth (CMT) type 1 on EDX by:

Accepted Answer

Acquired features in CIDP: conduction block, temporal dispersion, and asymmetric slowing versus uniform slowing in CMT

Answer

CIDP shows acquired, often asymmetric demyelination with conduction block and temporal dispersion, while CMT1 shows uniform, symmetric slowing without conduction block.

Question 3

A patient with wrist drop after humeral fracture has EDX showing preserved radial sensory SNAP amplitude. What does this suggest?

Accepted Answer

The lesion may be proximal to where the superficial radial sensory branch originates, sparing it

Answer

A preserved SNAP despite motor weakness suggests the sensory branch may be anatomically spared, or the timing of testing is too early for Wallerian degeneration to cause amplitude loss.

Question 4

In ALS, sensory nerve conduction studies are typically:

Accepted Answer

Normal or minimally abnormal, as ALS primarily affects motor neurons

Answer

ALS is primarily a motor neuron disease; sensory NCS are typically normal because sensory neurons and their axons are largely spared.

Question 5

EDX findings in critical illness myopathy (CIM) include:

Accepted Answer

Reduced CMAP amplitudes, short-duration MUPs with early recruitment, and reduced muscle membrane excitability

Answer

CIM shows reduced CMAP amplitudes (reflecting muscle membrane inexcitability), short-duration small MUPs (myopathic), and early recruitment on EMG.

(EDT) Electrodiagnostic Technician Certification Practice Test

(EDT) Electrodiagnostic Technician Certification Practice Test

EDT EDT Clinical Correlations & Pathology 2