L14 Clinical Neurophysiology

Question 1

what’s the utility of nerve conduction studies or electromyography?

Answer 1

localize lesion
characterize underlying nerve pathphysiology
assess severity and prognosis
assess age of nerve lesion
determine underlying basis for weakness

Question 2

which muscle is the reference electrode placed on for the motor conduction studies?

Answer 2

abductor pollucis brevis

Question 3

what is the Compound Muscle Action Potential (CMAP)?

Answer 3

summation of all individual muscle fibre action potentials

Question 4

what’s the Sensory Nerve Action Potential (SNAP)?

Answer 4

summation of all individual sensory fibre action potentials

Question 5

where to stimulate and record for sensory nerve conduction?

Answer 5

stimulate mixed motor/sensory nerve. record area that has no motor fibres.

Question 6

what does the needle electrode exam help answer?

Answer 6

age of lesion

recovery

Question 7

conduction block vs axonal loss?

Answer 7

axonal loss has loss of CMAP distal and proximal to the lesion, while conduction only shows loss proximal to the lesion

Question 8

how long does recovery from demyelination take?

Answer 8

1-3 months. usually complete

Question 9

which type of axons take longer to die distal to an injury?

Answer 9

sensory takes longer than motor to die.

Question 10

how long does it take to rule out an axonal loss lesion?

Answer 10

10 days

Question 11

what do fibrillations during relaxation of a needle electrode exam indicate?

Answer 11

axonal loss

Question 12

what type of signals do voluntary contractions produce during needle examination students?

Answer 12

motor unit potentials (MUPs)

Question 13

reduced recruitment in needle electrode exams indicates what type of lesion?

Answer 13

neurogenic lesion

Question 14

early recruitment in needle electrode exams indicates what type of lesion?

Answer 14

myopathic lesion