B7-013 Peripheral Neuropathies

Question 1

the spinal cord ends at what vertebral level

Answer 1

L1

Question 2

the lowest portion of the spinal cord is the

Answer 2

conus medullaris

Question 3

where does C8 nerve root exit the spinal cord?

Answer 3

below C7 vertebrae
above T1 vertebrae

Question 4

roots C1-C7 exit […] their respective vertebrae

Answer 4

above

Question 5

lumbosacral and thoracic roots exit […] the correspondingly numbered vertebral bones

Answer 5

below

Question 6

lumbrosacral roots travel several levels […] before exiting the spinal canal

Answer 6

caudally

Question 7

typically, a disk herniation will effect the […] roots

Answer 7

lower

Question 8

central disc herniations at the level of […] can impinge roots lower than the level of herniation

Answer 8

cauda equina

Question 9

central disc herniations above […] can compress the cord causing conus medullaris syndrome

Answer 9

L1

Question 10

extreme lateral disc herniations can effect the […] root

Answer 10

upper

Question 11

apical lung lesions and thoracic outlet syndrome would effect the […] brachial plexus

Answer 11

lower

Question 12

the upper brachial plexus is most commonly affected by […] in adults

Answer 12

trauma

Question 13

the […] plexus runs through the retroperitoneal space

Answer 13

lumbosacral

**can be damaged by retroperitoneal hematoma or psoas abscess

Question 14

cause of meralgia parethetica

Answer 14

lateral femoral cutaneous being trapped below the ilioinguinal ligament

Question 15

cause of piriformis sciatica

Answer 15

sciatic nerve entrapped beneath the piriformis muscle

Question 16

cause of peroneal nerve entrapment

Answer 16

entrapment of the common fibular nerve at the fibular head

Question 17

cause of carpal tunnel syndrome

Answer 17

median nerve entrapment at carpal tunnel

Question 18

cause of cubital tunnel syndrome

Answer 18

ulnar nerve entrapment at cubital tunnel

Question 19

cause of Guyon’s canal

Answer 19

ulnar nerve entrapment at the wrist

Question 20

why do disc herniations in the lumbar spine affect the lower root?

Answer 20

posterolateral dislocation impinges the root on its way to the next level

Question 21

NCS typically measure the function of […]

Answer 21

large myelinated nerves

this is why patients with small fiber neuropathy can have normal NCS

Question 22

if you have a disease causing nerves to die, the […] will be decreased on NCS

Answer 22

amplitude

Question 23

if you have a disease affecting the myelin, the […] will be decreased on NCS

Answer 23

velocity

Question 24

relatively preserved amplitude of response

Answer 24

myelinopathy

Question 25

very slow velocities, long latencies, conduction block

Answer 25

myelinopathy

Question 26

low amplitude response

Answer 26

axonopathy

Question 27

relatively preserved velocities

Answer 27

axonopathy

Question 28

spontaneous muscle activity on EMG shows

Answer 28

fibrillation (**acute nerve denervation**) fasciculation

Question 29

a single muscle fiber spontaneously firing

Answer 29

fibrillation (acute denervation)

Question 30

an entire motor unit spontaneously firing

Answer 30

fasciculation (like eyelid twitch)

Question 31

what would this pattern indicate?

Answer 31

chronic denervation/reinnervation

Question 32

how are compound muscle action potentials measured?

Answer 32

using two stimulation points

Question 33

how are sensory nerve action potentials measured?

Answer 33

directly off the nerve

Question 34

typical nerves conduction velocities are around

Answer 34

50 m/sec

Question 35

relatively preserved amplitude, slow conduction

Answer 35

demyelinating neuropathy

Question 36

decreased amplitude, normal conduction velocity

Answer 36

axonal neuropathy

Question 37

M waves

Answer 37

compound motor action potential

Question 38

F waves

Answer 38

retrograde conduction to spinal cord along the motor axon

Question 39

H reflex

Answer 39

deep tendon reflex stimulated electrically

Question 40

describe EMG changes from acute denervation

Answer 40

fibrillations

Question 41

describe EMG changes from chronic denervation

Answer 41

subsequent reinnervation causes large, wide complicated motor units

Question 42

SNAPs are [...] in radiculopathies

Answer 42

normal (**abnormal in plexopathy**)

Question 43

why are SNAPs normal in radiculopathies?

Answer 43

the sensory nerve cell body is distal to the damage so the axon doesn't die

Question 44

situations where NCV/EMG has poor sensitivity [4]

Answer 44

early disease mild disease focal neuropathy small fiber neuropathy

Question 45

SNAPs are [...] in plexopathies

Answer 45

abnormal

Question 46

fibrillation potentials in the cervical paraspinals would indicate damage to

Answer 46

cervical nerve root **paraspinals are innervated by the dorsal root**

Question 47

cervical nerve roots exiting the vertebral formina exit [...] the correspondingly numbered vertebrae

Answer 47

above

Question 48

located anatomically near the brachial plexus mediates pupillary dilation

Answer 48

ascending sympathetics

Question 49

in a patient with weakness/numbness of the arm, involvement of the ascending sympathetics indicates involvement of the

Answer 49

brachial plexus

Question 50

burning pain between the thumb and index finger is caused by

Answer 50

handcuff neuropathy due to compression of the superficial radial nerve

Question 51

generally, are EMG/NCS helpful for focal neuropathies?

Answer 51

no

Question 52

when pathology is distal to the root, the paraspinal muscles will be [...] on EMG

Answer 52

spared

Question 53

when pathology involves the root, paraspinal muscles will be [...] on EMG

Answer 53

affected

Question 54

causes of meralgia parethetica

Answer 54

weight gain tight belts tool belts

Question 55

leprosy has what pattern?

Answer 55

cool dependent pattern of involvement (used to be the most common cause of cool dependent neuropathy)