EMG/NM

Question 1

Define innervation ratio

Answer 1

amount of fibers belonging to an axon is the innervation ratio

Question 2

EDX studies evaluate only ______ fibers

Answer 2

Ia

Question 3

What happens with the following parameters of nerves with temperature decreasing from 32 to 30? Latency, amplitude, duration, conduction velocity, phases

Answer 3

Prolonged, increased, increased, decreased, increased

Question 4

Propagation of nerve signal along axon is known as

Answer 4

saltatory conduction (going from one node to another)

Question 5

How much ACh molecules per quanta? How wide is synaptic cleft?

Answer 5

5000-10000 molecules;

200-300 Angstroms

Question 6

Sarcomere runs from;

what binds to troponin-tropomyosin complex?

Answer 6

Z-line to Z-line;

Calcium

Question 7

Axonal regrowth occurs approximately

Answer 7

1 mm/day, or 1 in/month

Question 8

Ohm’s Law

Answer 8

Current = Voltage/resistance

Question 9

Which needle requires a separate reference electrode to perform EMG?

Answer 9

Monopolar

Question 10

What could potentially happen with reversal of stimulator’s cathode and anode?

Answer 10

Anodal block; hyperpolarization of nerve and inhibition of AP production

Question 11

CV of newborn is _____ % of an adult; at 1 year, ____ % of an adult; what age is CV that of an adult?

Answer 11

50%;
80%;
3-5 yrs of age

Question 12

CV drops _______ m/sec per 1 degree dropped

Answer 12

2.4

Question 13

H-reflex: what type of reflex? Initiated with what type of stimulation? Stimulates what type of fibers, causing _______ sensory and motor responses

Answer 13

Monosynaptic effectively;
submaximal;
1a afferent;
orthodromic

Question 14

A wave occurs at ______ latency

Answer 14

constant

Question 15

What is synkinesis?

Answer 15

Aberrant regen of axons after facial nerve injuries leading to re-innervation of inappropriate muscles (lip twitching with closing eye; crocodile tears when chewing)

Question 16

What does SSEP monitor for?

Answer 16

1. Peripheral nerve injuries
2. CNS lesions like MS
3. Intra-operative monitoring of spinal surgery

Question 17

Median nerve SSEP markers: N9, N11, N13, P14, N18, N20?

Answer 17

N9: Erb's point
N11: Roots
N13: Cervicomedullary junction
P14: Lower brainstem
N18 Rostral brainstem
N20 Primary cortical somatosensory receiving area

Question 18

MEPPs represent

Answer 18

release of individual quanta across NMJ

Question 19

When do you see satellite potentials?

Answer 19

Early reinnervation and trail main MUAP; time-locked potentials

Question 20

Optimal # of muscles to screen for cervical or lumbar radic?

Answer 20

6 muscles if paraspinals are included

Question 21

Muscles with dual innervation

Answer 21

Pec major, brachialis, FDP, lumbricals, FPB, pectineus, adductor magnus, biceps femoris

Question 22

With nerve root avulsion, see ______ CMAP’s with _______ SNAP’s

Answer 22

absent, normal

Question 23

What does AIN supply?

Answer 23

FPL, 1/2 of FDP, and PQ

Question 24

In CTS maximal slowing is across the _________, whereas in peripheral neuropathy, the _______ ________ is more abnormal

Answer 24

wrist;

distal segment

Question 25

What does initial positive deflection of median nerve CMAP at antecubital fossa but not at wrist mean? Where would the higher CMAP amplitude be?

Answer 25

Martin-Gruber anastomosis;

elbow

Question 26

What’s a Riche-Cannieu anastomosis?

Answer 26

Connection of recurrent branch of median nerve in hand to deep motor branch of ulnar nerve (ulnar hand)

Question 27

Radial nerve muscles innervated below the spiral groove?

Answer 27

BR, ECRL

Question 28

Where is a Monteggia fx?

Answer 28

Proximal 1/3 of the ulna with dislocation of the radial head

Question 29

What is the only peripheral nerve injury localized to the trunk level?

Answer 29

Suprascapular neuropathy

Question 30

What muscle technically innervated by peroneal nerve is spared with common peroneal neuropathy?

Answer 30

Short head of biceps femoris

Question 31

EMG recording of the external anal sphincter has ______ activity at rest. What is seen during defecation with regards to activity?

Answer 31

continuous;

Preserved or increased activity during prolonged substantial rectal distension during defecation

Question 32

What is often the first sign in AIDP/GBS? What means poorer prognosis for those with GBS?

Answer 32

Ascending numbness;

CMAP amplitude < 20%, nerve CV < 40%, F-wave absent

Question 33

Most common type of neuropathy for HIV patients?

Answer 33

Distal symmetric polyneuropathy (sensory and autonomic fibers)

Question 34

For rep nerve stim (RNS), decrease of greater than _______ % amplitude from first to fifth waveform is significant

Answer 34

10

Question 35

Define jitter

Answer 35

Prolonged time between interpotential discharges of muscle fibers belonging to same motor unit

Question 36

Central core disease associated with

Answer 36

malignant hyperthermia

Question 37

Where do you most commonly see abnormal activity on EMG in poly/dermatomyositis?

Answer 37

Paraspinals

Question 38

What is the ambulation status of each type of SMA?

Answer 38

SMA1: Never sits independently
SMA2: Independent sitting, assistive device for standing and walking
SMA3: Independent standing/walking

Question 39

Findings on SFEMG for ALS?

Answer 39

Increased jitter and fiber density