Peripheral Nerve Diseases

Question 1

resting membrane potential

Answer 1

-70 mb

more K than Na

Question 2

definition of neuropathy vs neuronopathy

Answer 2

neuropathy: lesion either IN the cell body or the PERIPHERAL PROCESS
neuronopathy: lesions TO the cell body

Question 3

mechanisms of pni

Answer 3

compression
sheath loss or demyelination
disconnection
degeneration

Question 4

mechanisms of neuronopathy

Answer 4

anterior horn cell lesions = motor neuron disease

dorsal root ganglion lesions = sensory neuronopathy

Question 5

seddon classsification for peripheral neuropathy

Answer 5

neurapraxia = myelin
axonotmesis = myelin and axon
neurotmesis = whole nerve

Question 6

suderland classification for peripheral neuropathy

Answer 6

1: conduction block: focal myelin injury or conduction block
2: axonal discontinuity: axon injured, neuriums intact
3: axonal and endoneurium
4: axon, endoneurium, perineurium
5: whole nerve

Question 7

what is allodynia, hyperalgesia, and myokymia

Answer 7

allodynia: pain from non-noxious stimulus
hyperalgesia: enhanced pain from noxious stimulus
myokymia: worm-like or ripping movements of muscles on eyelids

Question 8

presentation of myelinopathy

Answer 8

weakness without atrophy
length independent symptoms or distribution
proximal predominant or asymmetric/patchy distribution
early involvement of the reflexes

Question 9

presentation of axonopathy

Answer 9

length-depended distribution

distal reflex loss with preserved proximal reflexes (LE > UE)

Question 10

post-nerve biopsy complications

Answer 10

permanent numbness
neuropathic pain
painful neuroma formation

Question 11

indications for nerve biopsy

Answer 11

amyloid neuropathy

vasculitis

Question 12

sites commonly tested for nerve biopsies

Answer 12

sural nerve
superficial radial nerve
superficial peroneal nerve + peroneus brevis muscle

Question 13

sensory nerve conduction series results for demyelination and axonal loss

Answer 13

demyelination: abnormal latencies and conduction velocities, temporal dispersion
axonal loss: decreased amplitude

Question 14

motor nerve conduction study results for demyelination and axonal loss

Answer 14

demyelination: abnormal latency and conduction velocity, temporal dispersion, conduction block
axonal loss: decreased amplitude

Question 15

emg findings in neuropathies

Answer 15

increased in spontaneous and insertional activities (fibrillation potential and positive sharp waves)
reduced recruitment pattern
motor unit aps (large amplitude, prolonged duration, polyphasic)

Question 16

most common cause of acute generalized weakness

Answer 16

gbs

Question 17

presentation of gbs

Answer 17

acute illness 1-2 weeks prior to onset of neuro symptoms
ascending numbness and paresthesia
progressive weakness
hypo- or areflexia
autonomic instability

Question 18

pathogenesis of gbs

Answer 18

not fully understood but assumed antibodies formed from the initial infection attach the body’s own nerves (myelin sheath)

Question 19

frequent cn palsies in gbs

Answer 19

cn 7, 3, 4, 5, 6, 9, 11

Question 20

csf features in gbs

Answer 20

elevated csf protein, <10 mononuclear cells/mm3

Question 21

electrodiagnostic findings in gbs

Answer 21

ncv slowing/conduction block
patchy reduction in ncv <10% normal
latency increased to 125-50% of normal (slow)

Question 22

what is miller fisher syndrome

Answer 22

more common in males, >40 yo
triad: ataxia, areflexia, ophthalmoplegia
most common complaint: diplopia

Question 23

what is chronic demyelinating polyradiculopathy

Answer 23

immune-mediated, relapsing or progressive course for at least 2 months or 8 weeks
(+) history of antecedent infection
(+) motor and sensory symptoms
(+) proximal and distal weakness

Question 24

clinical presentation of multifocal motor neuropathy

Answer 24

asymmetric weakness and atrophy in the distribution of individual peripheral nerves
usually misdiagnosed as ALS

Question 25

lab/emg features of mmn

Answer 25

(+) igm antibodies to gm1 or gm2 gangliosides | emg: demyelinating findings als: axonopathy

Question 26

neuropathies associated with infections

Answer 26

hiv (usually distal symmetric polyneuropathy) | herpes varicella zoster

Question 27

clinical presentation of herpes varicella zoster virus

Answer 27

(+) pain and paresthesia in dermatomal distribution followed by vesicular rashes after >1 week (+) postherpetic pain (T1-T12 > cn v1 > L2-S4) involvement of motor nerves (cn7 / ramsay hunt syndrome > cervical and lumbosacral > thoracic)

Question 28

most common metabolic disease correlated with neuropathy

Answer 28

diabetes mellitus

Question 29

most common form of dm neuropathy

Answer 29

diabetic distal symmetric sensory or sensorimotor polyneuropathy

Question 30

course and symptoms of DDSS/SP

Answer 30

sensory loss beginning at toes, gradual progression over time to involve legs then hands (+) tingline, lancinating pain, burning and deep aching pains sensory loss to all modalities in stocking-glove distribution

Question 31

most common toxic neuropathies

Answer 31

alcohol, isoniazid, ethambutol

Question 32

what are radiculopathies

Answer 32

arise from process that affects the nerve root | may be due to compressive or non-compressive causes

Question 33

presentaiton of radiculopathies

Answer 33

dermatomal or myotomal distributions radiating pain weakness, numbness, decreased reflexes

Question 34

types of radiculopathies

Answer 34

direct neural compromise (acute herniated nucleus pulposus, excess bony formation and spurring, hypermobility of vertebral segment) vascular compromise (compression, inflammatory response) -- can also lead to spinal nerve compression

Question 35

clinical presentation of cervical radiculopathy

Answer 35

pain, numbness, and tingling sensation in the spinal nerves affected (severe: motor weakness and atrophy) (+) spurling test

Question 36

distributions of cervical radiculopathy

Answer 36

c5, c6: deltoid c7: triceps (most common) c8: thenar eminence t1: first dorsal interosseous

Question 37

clinical presentation of lumbosacral radioculopathy

Answer 37

pain in the lower back or leg numbness and tingling sensation in le (+) straight leg test

Question 38

what is brachial plexopathy

Answer 38

peaks during birth or age of 2-30 years erb's palsy: c5-c6 klumpke's paralysis: lower brachial plexus

Question 39

what is lumbosacral plexopathy

Answer 39

lumbar plexus: l1-l4 | sacral plexus: l5-s2/s3

Question 40

pathophysiology of entrapment neuropathies

Answer 40

develop at common sites of chronic or recurrent constriction | due to pressure, stretch, angulation, or friction

Question 41

most common entrapment neuropathy

Answer 41

carpal tunnel syndrome, entrapment of median nerve | more common in females

Question 42

clinical presentation and causes of carpal tunnel syndrome

Answer 42

pain and numbness in first 1/4 of fingers weakness and atrophy of the thenar eminence causes: tenosynovitis, trauma, tumors

Question 43

what is cubital tunnel syndrome

Answer 43

entrapment of ulnar nerve at elbow region causes: chronic irritation, tumors, valgus deformity

Question 44

what is sciatica

Answer 44

entrapment of sciatic nerve due to overuse or compression | presents with pain in hip, buttock, and radiating down the leg

Question 45

what is tarsal tunnel syndrome

Answer 45

entrapment of posterior tibial nerve in tarsal tunnel (medial malleolus, medial calcaneal wall, flexor retinaculum) presents with pain at medial hind foot or plantar aspect of foot

Question 46

most common inherited neuromuscular disorder

Answer 46

charcot marie tooth disease

Question 47

features of cmt disease

Answer 47

``` slowly progressive, with onset in first decade distal muscle wasting and weakness reduced or absent tendon reflexes distal sensor loss high incidence of foot deformities ```

Question 48

features of cmt1

Answer 48

table 10

Question 49

features of cmt2

Answer 49

table 11