Electrodiagnostic Studies

Question 1

What 3 abnormal spontaneous activities seen on EMG arise from motor unit pathology

Answer 1

1. Fasciculations
2. Myokymic discharges
3. Neuromyotonic discharge

Question 2

What happens to SNAP in ALS

Answer 2

Normal

Question 3

Amplitude of fibs and PSWs

Answer 3

Fibs = ~300 microvolts
PSWs = ~1000 microvolts

Question 4

What is the initial deflection of myotonic discharge

Answer 4

Varies - can be positive deflection or biphasic or triphasic

Question 5

What 2 muscles can you use for H-reflex

Answer 5

FCR and gastroc-soleus

Question 6

what type of neuropathy is seen in diabetic neuropathy

Answer 6

axonal and demyelinating sensory motor neuropathy

Question 7

Normal amplitude of a MUAP

Answer 7

1 mV

Question 8

what is the correlation between firing frequency and recruitment pattern

Answer 8

increased firing frequency = decreased recruitment

Question 9

Are large amplitude long duration MUAPs seen in myopathic or neuropathic processes

Answer 9

Neuropathic

Question 10

Normal duration of a MUAP

Answer 10

5-15 ms

Question 11

Are short duration small amplitude MUAPs seen in myopathic or neuropathic processes

Answer 11

Myopathic

Question 12

in the newborn, nerve CV are what percentage of adult values

Answer 12

50%. 1 yo = 75% of adult values

Question 13

What denervation potential sounds like dive bomber

Answer 13

Myotonic discharge

Question 14

what type of neuropathy is seen in alcohol neuropathy

Answer 14

axonal sensory motor neuropathy

Question 15

SSEPs only evaluates nerve fibers that sense _________ and __________

Answer 15

Vibration and proprioception

Question 16

In a neuropathic process, what happens to recruitment pattern

Answer 16

Reduced recruitment

Question 17

What 4 abnormal spontaneous activities seen on EMG arise from muscle or nerve pathology

Answer 17

1. Fibs
2. PSWs
3. Myotonic discharge
4. Complex repetitive discharge

Question 18

What happens to MUAP amplitude, duration, and recruitment in myopathy?

Answer 18

Small amplitude, short duration, early recruitment

Question 19

What nerves are commonly used for testing in somatosensory evoked potentials

Answer 19

Median nerve for upper limb and tibial nerve for lower limb

Question 20

What denervation potential sounds like motor boat

Answer 20

CRDs

Question 21

What do somatosensory evoked potentials test?

Answer 21

Ascending sensory pathways to the somatosensory cortex

Question 22

In normal recruitment, what is the frequency of firing rate

Answer 22

Every 5 Hz another motor unit fires

Question 23

Which denervating potential sounds like marching soldiers

Answer 23

Myokymic discharge

Question 24

Miniature end plate potentials is also known as

Answer 24

Endplate noise

Question 25

side to side latency of H-reflex is significant if it is greater than what?

Answer 25

1.5 ms

Question 26

Are SSEPs done with submaximal or supramaximal stimulation?

Answer 26

Submaximal

Question 27

normal gain for sensory nerve study

Answer 27

20 microvolts/division

Question 28

What happens to conduction velocity if measured distance is falsely low

Answer 28

Conduction velocity will be falsely decreased. (Measured distance is 10cm, when it is actually 15cm will give you a slow conduction velocity when it is actually faster)

Question 29

Amplitude of miniature endplate potentials

Answer 29

10 to 50 microvolts

Question 30

Which denervating potential resembles a MUAP

Answer 30

Fasciculations

Question 31

What causes miniature end plate potentials

Answer 31

Release of individual quanta of ACh

Question 32

what happens to latency, CV and amplitude in a cold limb

Answer 32

latency increases CV decreases amplitude increases

Question 33

what type of neuropathy is seen in paraneoplastic syndrome

Answer 33

axonal sensory neuropathy

Question 34

What 3 main problems do SSEPs monitor for

Answer 34

1. Peripheral nerve injuries 2. Central nervous system lesions 3. Intraoperative spinal surgery monitoring