Peripheral neuropathy

Question 1

How do you distinguish nerve root compression from peripheral neuropathy

Answer 1

peripheral neuropathy should demonstrate autonomic changes

nerve root compression should not
(autonomic sympathetic fibers join peripheral nerves distal to the junction of the anterior and posterior rami)

Question 2

What are the molecular machiner for anterograde and retrograde movement in neurons? (Fast axonal transport system - FAT)

Answer 2

Kinesin - anterograde

Dynein - retrograde

Question 3

What is wallerian degeneration?

Answer 3

swelling then dissolution of axon/myelin

• develops distal to the site of injury
• takes several weeks to months

Question 4

Segments of myeline loss between nodes of ranvier w unaffected myelin below and above it
onion bulb

Answer 4

Segmental degeneration

Question 5

What is chromatolysis?

Answer 5

occurs when Wallerian degeneration is near a cell body

= cell body swelling, dissolution of ER (Nissl substance) and eccentric localization of the nucleus

Question 6

Dying of axon and myeline

spares schwann cell body

Answer 6

Axonal degeneration

Question 7

What type of peripheral neuropathy can develop into painful to minor touch
histology: concentric fibrous bands in the perineurium and epineurium

Answer 7

Neuroma - Axonal degeneration - if cell body is spared, and new axons redevelop aberrantly (Morton’s neuroma)

Question 8

Post amputation tissue accumulation at the stump

Answer 8

pseudoneuroma - not as painful

Question 9

Which neuronal cells clean up damaged tissue?

Answer 9

Schwann cells

Macrophages

Question 10

damage involving nerve cell body and axons, motor or sensory

Answer 10

neuronopathy

Question 11

distal symmetric loss of both axons and myelin

Answer 11

Generalized polyneuropathy

Question 12

nerve damage from focal trauma, immune deposition, infection, systemic disease

Answer 12

Mononeuropathies

Question 13

What type of factors are small sensory fiber nerve most susceptible to? what are Sx (1 example disease)?

Answer 13

Painful parethesia, loss of light touch, pain

susceptible to:

1. IgM deposition (Waldestrom macroglobulinemia)
2. Chemo agents
3. Diabetes

Question 14

What type of factors are large fiber nerves most susceptible to? what are sx (2 diseases)?

Answer 14

loss of vibratory, proprioceptive, light touch

Gullain-Barre syndrome (post infectious polyradiculoneuropathy)

Vit B 12 deficiency

Question 15

What is Guillain-Barre syndrome?

Answer 15

demyelination from post infectious inflmmatory response

• Motor>sensory
• URI/GI, EB virus, CMV, HIV, Lyme, Camylobacter jejuni

Question 16

How do you identify Guillain-Barre through lumbar puncture?

Answer 16

look for cytoalbumin dissociation (no cells, high protein)

Question 17

minor extremity parethesias followed by progressive paralysis ascending from lower extremities cephalad

or presenting w cranial nerve motor nerve palsies w/ or w/o appendicular involvement

respiratory failure is common

Answer 17

Guillain-Barre syndrome

Question 18

young person
abdominal pain
proximal neuropathy
psychosis

Answer 18

porphyria

Question 19

What neuropathy is common with monoclonal gammopathy?

Answer 19

Osteosclerotic myeloma
= POEMS
polyneuropathy, organomegally, endocrinopathy, monoclonal IGM, skin changes) - a/w lambda light chain

a/w Anti-Mag Abs

Question 20

diminished sensory in hands, lower extremity and STERNUM

Answer 20

HIV peripheral neuropathy

Question 21

What are the following types of hereditary neuropathies

1. Type 1
2. Type 2
3. Type 3

Answer 21

1. Demyelinating - onion bulb
2. Axonal - atrophic nerves
3. infantile hyperrtrophic neuropathies - onion bulb

type 1Autosomal dominant = most common

Question 22

What is the chromosomal abnormality for the most common type of hereditary neuropathy?

Answer 22

most common: Type 1 A (autosomal dominant)

PMP22 on chromosome 17 is most common

Question 23

What type of neuropathy is it most likely when the pt has disfigured extremities (high arch/hammer toe, claw hand with severe atrophy, champagne bottle legs)

Answer 23

Hereditary neuropathy

Question 24

How does diabetes cause neuropathy?

Answer 24

1. loss of vascular supply

2. Loss of neural trophic factors

Question 25

neuropathy with sensory loss in the alar region of the face?

Answer 25

Leprosy related neuropathy

Question 26

Patients will state they developed weakness and sensory loss definable to individual nerves in an asymmetric pattern over weeks or months in a stair step pattern.

Answer 26

Mononeuritis Multiplex (inflammatory/autoimmune)

lupus, Wegener granulomatosis
Sarcoidosis
Lyme disease
Toxins - Lead = Wrist drop!!

Question 27

Which nerve is entrapped in crutch palsy

Answer 27

Radial N

Question 28

What is the sensory loss of compression of the ulnar N at the cubital tunnel?

Answer 28

loss of:
palmar
superficial
dorsal branches

Question 29

What is the sensory loss of compression of the ulnar N at the Guyon’s Canal?

Answer 29

loss only at superficial branch - tips of 4th and 5th on palmar side

Question 30

What is Saturday night palsy? what are Sx?

Answer 30

Radial neuropathy at surgical groove

• Forearm extensor weakness - wrist drop
• Sensory loss - anatomic snuff box region