EDT EDT EMG Waveform Analysis

Question 1

Fibrillation potentials on needle EMG represent:

Accepted Answer

Spontaneous discharge of individual denervated muscle fibers

Answer

Voluntary firing of normal motor units

Answer

Fasciculation of an entire motor unit

Answer

Normal insertional activity

Question 2

Positive sharp waves (PSWs) on EMG are considered abnormal when:

Accepted Answer

They persist beyond needle movement and occur spontaneously at rest

Answer

They occur only with needle insertion

Answer

They appear during voluntary contraction

Answer

They are seen only in paraspinal muscles

Question 3

Fasciculation potentials differ from fibrillation potentials in that fasciculations:

Accepted Answer

Represent spontaneous discharge of an entire motor unit

Answer

Are smaller in amplitude and shorter in duration

Answer

Occur only in denervated muscle fibers

Answer

Are always pathological

Question 4

Which EMG finding is most characteristic of chronic denervation with reinnervation?

Accepted Answer

Large amplitude, long-duration polyphasic MUPs with reduced recruitment

Answer

Small, short-duration polyphasic MUPs

Answer

Fibrillations with normal MUP morphology

Answer

Early recruitment with normal MUP size

Question 5

The recruitment pattern in a myopathic process typically shows:

Accepted Answer

Early recruitment with small, short-duration MUPs

Answer

Reduced recruitment with large MUPs

Answer

Discrete pattern at maximal effort

Answer

Absent voluntary activity

Question 6

Complex repetitive discharges (CRDs) on EMG are best described as:

Accepted Answer

Uniform repetitive discharges with abrupt onset and cessation, indicating chronic muscle denervation or myopathy

Answer

Normal activity seen in healthy muscle at rest

Answer

Bursts of activity seen only during voluntary contraction

Answer

High-amplitude potentials specific to ALS