EDT EDT EMG Waveform Analysis 1

Question 1

Fibrillation potentials on needle EMG represent:

Accepted Answer

Spontaneous discharge of individual denervated muscle fibers

Answer

Fibrillation potentials represent spontaneous discharges of single denervated muscle fibers that have become hyperexcitable after losing their nerve supply.

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

PSWs are abnormal when they occur spontaneously at rest beyond the area of needle insertion, indicating denervation or muscle membrane instability.

Question 3

Fasciculation potentials differ from fibrillation potentials in that fasciculations:

Accepted Answer

Represent spontaneous discharge of an entire motor unit

Answer

Fasciculation potentials represent the spontaneous, involuntary discharge of an entire motor unit, appearing as complex polyphasic potentials of larger amplitude.

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

Chronic denervation with reinnervation produces large-amplitude, long-duration polyphasic MUPs due to collateral sprouting and motor unit enlargement.

Question 5

The recruitment pattern in a myopathic process typically shows:

Accepted Answer

Early recruitment with small, short-duration MUPs

Answer

Myopathies reduce the force-generating capacity of individual muscle fibers, requiring more motor units to fire early to compensate, producing early recruitment of small MUPs.

(EDT) Electrodiagnostic Technician Certification Practice Test

(EDT) Electrodiagnostic Technician Certification Practice Test

EDT EDT EMG Waveform Analysis 1