CNS2 Flashcards
Neuronal injuries affecting axons (axonopathies) - list three
Wallerian degeneration; proximal axenopathy; distal axonopathy
Neuronal injuries affecting the cell body of the neuron - list three
Central chomatolysis; inclusions; neuronal necrosis and its resolution (differs from pannecrosis)
Some conditions affecting the neuron can affect only the axon, and are at least theoretically reversible. True or False.
True - If you have axonal injury you have some hope for regeneration - neurons will try to regenerate their processes
Wallerian Degeneration is the most common axonopathy in vet med. True or False.
True
Wallerian degeneration follows ____ or ____ axonal transection/separation) in PNS or CNS.
Physical or functional
Wallerian Degeneration –> ___ and ____ degeneration together.
Axon and myelin
What is the first step (can occur within minutes) in Wallerian Degeneration? (following trauma vs. ischemia secondary to compression)
Cytoskeletal degeneration in the axon; microfilaments fall apart; in trauma = dephosphorylation of neurofilament arms; in ischemia secondary to compression = ATP reduction –> leads to a transport blockade
In Wallerian Degeneration, cytoskeletal degeneration in the axon leads to ______ of axon ____.
Denaturation of axon proteins
Wallerian degeneration (PNS) - in 24 hours, what is the finding?
Tissue collapse
Wallerian degeneration (PNS) - in 2-10 days, what is the finding?
Phagocytosis of debris; muscle atrophy; attempted regeneration (neuron shifts from making synaptic vesicles to structural parts of the axon - and sends it down to the ends of the axon and starts proliferating axonal processes - axonal sheath is a good thing because you can’t get lost)
Wallerian degeneration (PNS) - in 2-3 weeks, what is the finding?
Remyelination with altered length between nodes if successful; Bungner’s bands and chronic atrophy if unsuccessful
Motor neurons start to make what growth factor that serves as a stimulus for axonal growth in motor neurons?
NGF - neuronal growth factor
If regeneration is successful, we get ____ atrophy.
Reversed
If regeneration is unsuccessful, we get ____ atrophy of distal nerve and muscle and _____ formation.
permanent; neuroma
What factors determine whether WD is repaired successfully?
Depends on success of axon regeneration - how well the proximal and distal ends of nerves are aligned; whether PNS vs CNS is involved; how close the transection is to the cell body
Where is regeneration more likely to occur, PNS or CNS and why?
PNS because PNS has a basement membrane - no BM in CNS
Brachial plexus avulsion (trauma-driven Wallerian degeneration in PNS)
Trauma drives the limb caudally along the body, pulls the spinal nerves away from the cord at vertebral foramina, first ventrally, then dorsally
Bunger’s bands are indication of successful resolution of WD and return of function. True or False.
False
A short time after brachial plexus avulsion (days) you could detect microscopic degeneration or loss of axons and myelin, and muscle atrophy. True of False.
True
Lesions associated with spinal cord compression: WD caused by ischemia –> most WD affects ____ funiculi most severely.
Ventral
Lesions associated with spinal cord compression: WD caused by ischemia: describe lesions listed in increasing severeity
With moderate ventral compression, ventral white tracts degenerate; Wallerian degeneration of lateral then dorsal funiculi as compression is more severe; Malacia of gray matter
Not all injuries will involve all funiculi at the site of compression. True or False.
True
When WD affects the spinal cord after a compressive insult, it is primarily a result of which process? Thrombosis, severed nerve roots, ischemia, inflammation?
Ischemia
What area of the cord would be affected first if compression occurred on the dorsal surface instead of ventrally?
Sensory
In “watershed lesions” of severe Wallerian Degeneration; posterior tot he site of greatest injury, what degenerates?
Ventral white tracts
In “watershed lesions” of severe Wallerian degeneration; cephalic to the site of injury, what degenerates?
Dorsal white tracts degenerate
Both posterior to the site of greatest injury and cepahlic to the site of injury in watershed lesions of severe Wallerian degeneration; cause axons distal to the cell body to degenerate, starting at the point of injury. True or False.
True
If a relatively mild ventral spinal cord compression causes WD limited to the ventral cord at TL, what lesion would be present in the dorsal white matter?
WD would not be present in dorsal white matter.
Type I intervetebral disk diseases causing WD
Occurs in old dogs; cervical; annulus fibrosis degenerates, protrusion
Type II intervertebral disk disease causing Wd
Occurs in chondrodystrophic dogs; T-L junction; nucleus pulposis degenerates; extrusion; multiple discs affected in 25% of affected Dachshunds
What is more severe, type I or type II intervetebral disk disease?
Type II
Equine cervical instability:
recurrent transietn deformation with vertebral over-riding
Equine vertebral affects young, growing male horses. specifically these breeds:
TB, TW, WB
Throwback, tenessee walker, warm blood
Equine vertebral instability affects which cervical vertebra?
C3-4, 5-6, 6-7