CNS, Pt. 2 Flashcards
(45 cards)
What are the 3 results of traumatic injuries to the brain? Are these types of injuries common in veterinary medicine?
- concussion - temporary loss of consciousness
- contusion - bleeding/bruising
- laceration - rupture of parenchyma
no - animals with 4 legs and smaller brains are less susceptible
What 3 motions cause traumatic brain injuries?
- axial - front to back
- angular - side to side
- rotational
What are coup and countercoup lesions?
- initial impact (coup - forward), causes a countercoup (backward) when brain strikes inside of the skull
- shaking disrupts the brain’s normal chemical balance, causing loss of consciousness
- brain swells, and in severe cases, puts pressure on the brainstem, which controls breathing and other basic life functions
What is a common brain lesion in boxers?
chronic repeated head trauma causes chronic traumatic encephalopathy, boxer’s encephalopathy, or dementia pugilistica —> neurofibrillary tangles
What is a common lesion in horses that have fallen backward?
basilar bone fracture —> head hits floor, resulting in ataxia and collapse
(requires a sagittal section of head to observe)
Injury to what artery results in cranial hemorrhage?
meningeal artery
What are 3 common causes of intrinsic spinal cord injuries?
- intervertebral disk disease
- vertebral abscesses
- cervical stenotic myelopathy (Wobbler disease) - Great Danes, Rottweilers, young horses
What is the most common etiology of polioencephalomalacia? What are 3 other causes?
(degeneration of gray matter in the brain)
thiamine deficiency
- sulfur toxicity: high sulfate in water, ingestion of sulfate-accumulating plants
- lead toxicity
- salt poisoning/water deprivation
Why does thiamine deficiency cause polioencephalomalacia? In what animals is this most common? What is the most common presentation?
vitamin B1 is necessary for brain health —> produced by bacteria in the rumen and dysbiosis may result in the proliferation of thiaminase-producing bacteria
young lambs and cattle
opisthotonus - marked dorsal extension of the head and neck in an arching position accompanied by rigid extension of the limbs (“stargazing”)
- dorsal medial strabismus and blindness is also common
How does polioencephalomalacia present grossly?
subtle pallor/yellowish discoloration (malacia) of the surface —> gray matter becomes harder to tell apart from white matter
Polioencephalomalacia, calf:
yellowish discoloration of cortical gray matter - degenerative necrosis
What is a common way to view polioencephalomalacia? In what situations does this occur?
autofluorescence under UV lights (Wood’s lamp)
only associated with thiamine deficiency (special pigment produced?) —> not all necrosis fluoresces
Chronic polioencephalomalacia, cattle:
cerebral cortical gray matter atrophy
What is the most common cause of polioencephalomalacia in pigs and poultry?
salt poisonin/water deprivation common due to salty feed and winter freezing of pipes
Polioencephalomalacia, pigs:
- most common cause is salt poisoning/water deprivation
- pink, necrotic, shrunken neurons with pyknotic nuclei
- spongiform change
Other than polioencephalomalacia, what can also be observed with salt poisoning/water deprivation in pigs and poultry?
perivascular and meningeal eosinophilic infiltration
What are 2 common causes of thiamine deficiencies in cats, dogs, and farmed mink/foxes? What is this called?
- diets containing fish as the primary ingredient, which contain high levels of thiaminase
- diets based entirely in cooked meat, since warming of the food can destroy thiamine
Chastek paralysis (foxes and mink**)
What is the distribution of lesion of polioencephalomalacia (Chastek’s paralysis) in cats, dogs, and wild carnivores?
brainstem —> malacia, necrosis, hemorrhage around ventricles
Chastek’s paralysis, histology, fox:
brainstem and hippocampus —> shrunken, eosinophilic neurons with spongiform change
What lesion on the brainstem is especially prominent in carnivores with thiamine deficiency?
necrosis of caudal colliculi with cavitation (prominent in carnivores)
(cats will commonly roll around with ventral flexion of head)
How is the CNS affected by severe liver disease?
neurological signs (worst after feeding) and polymicrocavitations/spongiform change of white matter (ballooning of myelin) caused by liver damage allowing accumulation of toxins like ammonia, short-chain fatty acids, and mercaptans in systemic circulation
(hepatic encephalopathy)
What causes focal symmetric encephalopathy? In what animals is this most common?
Clostridium perfringens type D epsilon toxin damages blood vessels in the brain near the basal nuclei/ganglia (floor of lateral ventricles)
sheep/lambs
Multifocal bilaterally symmetric encephalomalacia, lamb:
Clostridium perfringens type D - epsilon toxin (FSE)
(symmetric = toxin, not infection)
What causes moldy corn toxicity? In what animals is this most common?
ingestion of moldy feed, especially corn and corn byproducts contaminated by Fusarium verticillioides or proliferatum toxin, fumonisin B1
horses
