Block 2 #4 Flashcards
What is an example of a spinal reflex?
patellar reflex
What happens to spinal reflexes when LMN are involved?
Reduced or absent
What does it mean if a patient is positive on a crossed extensor?
UMN involvement
How is the neurological exam ordered?
Least offensive to most offensive
What is an important finding that owners may not bring up in diffuse LMN diseases?
Voice change
What lesion will cause LMN disease to both upper and lower limbs?
NONE!
What is an elephant on a beach ball posture from?
diffuse LMN disease
Do diffuse LMN patients have ataxia?
No
This is a CNS thing to have
What are 4 common diffuse LMN diseases?
Acute canine polyradiculoneuritis (coonhound paralysis)
Botulism
Tick paralysis
Myasthenia gravis
Do animals with diffuse LMN disease have patella reflex?
No
What is the mechanism of acute canine polyradiculoneuritis?
Immune-mediated
What is a time an animal can develop acute canine polyradiculoneuritis?
After rabies vaccine
What is the pathogenesis of ACP?
Production of autoantibodies against axons and myelin
What nerve roots are most affected?
Ventral - motor
Which anatomic nerve roots are most affected?
Lumbar and sacral (rear end)
What is a common symptom of ACP?
Change in bark (dysphonia)
What causes botulism?
Ingestion of neurotoxins of clostridium botulinum
Where do the neurotoxins come from?
Toxins in flesh (carrion) or spoiled food
Where do toxins enter the nervous system?
At the nerve endings
What is the molecular pathogenesis of botulism
Cleaves snap-25, VAMP, and syntaxin and prevent Act release from presynaptic terminal
What type of muscles are affected by botulism?
Smooth and striated muscles (all? lol)
What is the different between ACP and botulism on physical exam?
Megaesophagus common in botulism and not in ACP
Cranial nerves are affected in botulism but not in ACP
Compare progression of botulism to ACP
Botulism is 1-3 week recovery, much shorter
What is tick paralysis caused from?
tick paralysis
What is the pathogenesis of tick paralysis?
toxin interferes with function of Ca in the release of Ach
How long after tick attachment does it occur?
5-9 days
What is the difference between tick paralysis and the others?
Very rapid and death will occur if not removed fast enough
What is the most common diffuse LMN cause?
Myasthenia gravis
What are the 2 forms of myasthenia gravis?
Congenital vs acquired
What is the most common form of myasthenia gravis?
Acquired
What is the pathogenesis of myasthenia gravis?
Auto-antibody mediated destruction of Act receptors at the neuromuscular junction.
What are the 3 types of acquired myasthenia gravis?
Generalized (most common in vetted)
Focal
Fulminating (worse)
Where is the focal form limited to?
Esophagus
What is a differentiating thing about myasthenia gravis from the other diseases we’ve discussed?
Spinal reflexes are normally ok
What is the pathophysiology of myasenthia gravis?
Binding of autoantibodies to post-synaptic Ach receptor > compliment-mediated destruction of AchR
What is a very common symptom of dogs with myasthenia gravis?
Megaesophagus
How do you diagnose myasthenia gravis?
AchR autoantibody test
How is the congenital MG different?
No auto-immune component, just a defect in AchR
Why is swelling such a large problem in the brain?
Increases inter cranial pressure which reduces blood flow
What are the 4 mechanisms of edema in the brain?
Vasogenic
cytotoxic
intramyelinic
transependymal
What is vasogenic edema?
Leaky blood vessels
What is cytotoxic edema?
Rapid return to normal plasma osmolality where astrocytes cannot unload osmoses fast enough
What is the edema cycle?
A positive feedback loop between cytotoxic edema and vasogenic edema resulting in death
What is intramyelinic edema?
Splitting of myelin sheaths with fluid accumulation
What is transependymal edema?
Blockage of CSF flow, a slow loss of tissue
What is polioencephaloamalacia charactertized?
A morphological diagnoses
Where do ruminants need thiamine?
Cerebrocortical grey matter
When do ruminant get polio?
Ruminants can synthesize their own thiamine but when on high concentrate diets, this will lower rumen pH
How would a fat cat get thiamine polio?
Cats that go off food due to hepatic lipidosis (cats get thiamine in food)
What is chronic salt toxicity (bad name)
A morphological diagnosis of polio
Dehydrated animals are then given lots of fluid which changes the osmolality of the brain causing cytotoxic osmolality
What toxin-related polio can occur?
Large amounts of new feed stuffs are given
What are pigs especially susceptible to?
E coli
What are lambs especially susceptible to?
C. perfringens
What type of edema does salt toxicity trigger?
Cytotoxic
What type of edema does lead poisoning, endotoxins, and thiamine deficiency trigger?
Vasogenic edema
How does lead affect horses?
Much more sensitive than ruminants
Schwann cells, primary demyelination in PNS
What is infarction?
Tissue necrosis due to loss of blood flow
What is a septic emboli?
Embolism caused by bacteria that can get lodged in the brain
Thrombotic meningoencephalitis
What is the backup of blood supply to the grey matter of the spinal chord?
There isnt one!
It is an “end artery”
What happens if the end artery has an infarct?
malacia
What is pan necrosis?
Stoppage of all nutrient to the spot
What happens with a slow growing tumor?
Selective necrosis that doesn’t trigger the edema cycle
Is there hemorrhage with a concussion?
NO!
What is a concussion?
Transient stretching of white matter tracts in the brainstem
What is another word for contusion?
Bruising
What is avulsion?
Stretching of vessels resulting in tearing
What may a hematoma trigger?
Edema cycle due to increased pressure
What is delayed onset arteriospasm?
constricting of vessels but may lead to an infarct
What are the factors mediating potency of arterioles?
Endothelial relaxation factor
Prostacyclin
What does subarachnoid hemorrhage release?
Oxyhemoglobin
What does the oxyhemoglobin cause an accumulation of?
Diacylglycerol
Endothelin-1
What can blood migrate through?
White matter
What is the migration of blood through white matter called?
Ascending-descending myelomalacia
What does ischemia mean?
Inadequate blood supply to a tissue
Where does the end artery for grey matter branch from?
Ventral spinal artery
What is the worst consequence of disc herniation?
Hemorrhage into the subarachnoid space causing ascending-descending myelomalacia
What is Wallerian degeneration?
An insult that happens cranial to an axon causing the axons caudal to die
What are the 3 organizations of the CNS?
Motor system
Sensory system
Vestibular system
Where are sensory neurons located?
Ganglia of the dorsal nerve root
What CN is the vestibulocochlear?
VIII
What is wobblers characterized by?
Stenosis of the spinal canal
What are the 2 manifestations of wobblers?
Cervicovertebral instability (CVI)
Cervicovertebral static stenosis (CSS)
What is another term for wobblers
Cervicovertebral stenotic myelopathy (CVSM)
What is cervicovertebral instability?
Dynamic, intermittent compression
What is cervicovertebral static stenosis?
Static, continuous compression
Why are clinical symptoms worse in the read for cervicovertebral stenotic myelopathy?
Spinal tracts to the rear are more superficial
When does wobblers arise?
Usually earlier in life
What are the causes of wobblers?
Environmental and genetic
What is the best diagnostic for wobblers?
Minimal sagittal diameter (MSD)
What is minimal sagittal diameter?
Ratio of spinal diameter to vertebral body diameter
What MSD would be wobbler positive?
<50%
What is the symmetry of EPM?
asymmetric disease!
What is the definitive host of EPM?
Opossum
What parts of the body does EPM affect?
Spinal cord, brain stem, and cerebrum
What is another term for Equine herpes virus?
Myeloencephalopathy
What does EHV cause?
Abortion in mares and neonatal disease
Does all EHV cause myeloencephalopathy?
No!
What is the relevant factor in EDM?
Vitamin E deficiency
What is EMND?
Equine motor neuron disease
What does EMND originate from?
Neurodegenerative oxidative stress
Is there ataxia with EMND?
NO!
Is CVM or CVI more common in young animals?
CVI
What type of horses are predisposed to wobblers?
Horses growing fast!
What protozoa causes EPM?
Sarcocystis neurona
What is the respiratory presentation of EHV?
Rhinopneumonitis
What is the neurological manifestation of EHV?
EHM (myeloencephalotpathy)
What is a defining clinical sign of EHV?
Urinary incontenence
Rear limb lameness
What is a positive diagnostic of EHV?
Xanthochromic CSF
What does xanthochromic CSF mean?
Increased protein (yellow)
What does EMND (equine motor neuron disease) affect?
Gray matter
What does EDM (equine degenerative myelopathy) affect?
White matter
Does EMND or EDM have muscle atrophy?
EMND
EDM does not!
What is a distinct sign of EMND?
No ataxia
Is there ataxia in EDM? Muscle atrophy?
No muscle atrophy! Yes ataxia
What is the most common cause of lameness is perfomance horses?
Navicular disease (palmar heel pain)
Where does navicular disease normally impact?
Bilateral forelimb
What is laminitis?
Inflammation of hoof lamina (velcro of hoof)
What are causes of laminitis?
Hormones (Cushings)
Sepsis
Supporting limb laminates
What is a type I P3 fracture?
Non-articular, palmar process
What is a type II P3 fracture?
Articular, palmar process
What is a type III P3 fracture?
Sagital, articular
What is a type IV P3 fracture?
Extensor process
