Peripheral neuropathy Flashcards
How do you distinguish nerve root compression from peripheral neuropathy
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)
What are the molecular machiner for anterograde and retrograde movement in neurons? (Fast axonal transport system - FAT)
Kinesin - anterograde
Dynein - retrograde
What is wallerian degeneration?
swelling then dissolution of axon/myelin
- develops distal to the site of injury
- takes several weeks to months
Segments of myeline loss between nodes of ranvier w unaffected myelin below and above it
onion bulb
Segmental degeneration
What is chromatolysis?
occurs when Wallerian degeneration is near a cell body
= cell body swelling, dissolution of ER (Nissl substance) and eccentric localization of the nucleus
Dying of axon and myeline
spares schwann cell body
Axonal degeneration
What type of peripheral neuropathy can develop into painful to minor touch
histology: concentric fibrous bands in the perineurium and epineurium
Neuroma - Axonal degeneration - if cell body is spared, and new axons redevelop aberrantly (Morton’s neuroma)
Post amputation tissue accumulation at the stump
pseudoneuroma - not as painful
Which neuronal cells clean up damaged tissue?
Schwann cells
Macrophages
damage involving nerve cell body and axons, motor or sensory
neuronopathy
distal symmetric loss of both axons and myelin
Generalized polyneuropathy
nerve damage from focal trauma, immune deposition, infection, systemic disease
Mononeuropathies
What type of factors are small sensory fiber nerve most susceptible to? what are Sx (1 example disease)?
Painful parethesia, loss of light touch, pain
susceptible to:
- IgM deposition (Waldestrom macroglobulinemia)
- Chemo agents
- Diabetes
What type of factors are large fiber nerves most susceptible to? what are sx (2 diseases)?
loss of vibratory, proprioceptive, light touch
Gullain-Barre syndrome (post infectious polyradiculoneuropathy)
Vit B 12 deficiency
What is Guillain-Barre syndrome?
demyelination from post infectious inflmmatory response
- Motor>sensory
- URI/GI, EB virus, CMV, HIV, Lyme, Camylobacter jejuni
How do you identify Guillain-Barre through lumbar puncture?
look for cytoalbumin dissociation (no cells, high protein)
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
Guillain-Barre syndrome
young person
abdominal pain
proximal neuropathy
psychosis
porphyria
What neuropathy is common with monoclonal gammopathy?
Osteosclerotic myeloma
= POEMS
polyneuropathy, organomegally, endocrinopathy, monoclonal IGM, skin changes) - a/w lambda light chain
a/w Anti-Mag Abs
diminished sensory in hands, lower extremity and STERNUM
HIV peripheral neuropathy
What are the following types of hereditary neuropathies
- Type 1
- Type 2
- Type 3
- Demyelinating - onion bulb
- Axonal - atrophic nerves
- infantile hyperrtrophic neuropathies - onion bulb
type 1Autosomal dominant = most common
What is the chromosomal abnormality for the most common type of hereditary neuropathy?
most common: Type 1 A (autosomal dominant)
PMP22 on chromosome 17 is most common
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)
Hereditary neuropathy
How does diabetes cause neuropathy?
- loss of vascular supply
2. Loss of neural trophic factors
neuropathy with sensory loss in the alar region of the face?
Leprosy related neuropathy
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.
Mononeuritis Multiplex (inflammatory/autoimmune)
lupus, Wegener granulomatosis
Sarcoidosis
Lyme disease
Toxins - Lead = Wrist drop!!
Which nerve is entrapped in crutch palsy
Radial N
What is the sensory loss of compression of the ulnar N at the cubital tunnel?
loss of:
palmar
superficial
dorsal branches
What is the sensory loss of compression of the ulnar N at the Guyon’s Canal?
loss only at superficial branch - tips of 4th and 5th on palmar side
What is Saturday night palsy? what are Sx?
Radial neuropathy at surgical groove
- Forearm extensor weakness - wrist drop
- Sensory loss - anatomic snuff box region
