CVT Neurology Flashcards
What is status epilepticus?
Electrical Seziure activity at least 30 mins duration
What are cluster seizures?
Recurrent generalized epileptic seizure activity within 24 hours
What should you worry about in patients with status epilepticus?
7 yrs = Predisposing underlying brain dz
Which spp can have more rapid onset of cytotoxicity in status epilepticus?
Cats
What are the 2 main causes of neuronal death in status epilepticus?
Direct cytotoxicity of seizure (hypoxemia, ischemia, excitotoxicty)
Excitotoxicity - Excessive acitvation of glutamate receptors (excitatory) = Prolonged influx of Ca2+ into cell = Disruption of cellular metabolism
Which vitamin is a cofactor for cerebral aerobic glycolytic metabolism?
Thiamine
Why is bromide not recommended in cats?
High prevalence of adverse respiratory problems
What is the name of keppra and what is the MOA?
Levetiracetam - Binds to SV2A = synaptic vesicle protein
What is the MOA of gabapentin?
Structural analog to GABA
Inhibits voltage-gates Ca2+ channels in brain
What has been shown with gabapentin and seizures?
Mixed results = No benefit or slight benefit in reducing seizures
What is pregabalin?
Gabapentin analog - Increased affinity to subunit of voltage-gates Ca2+ channel
What is felbamate’s MOA?
Dicarbamate drug = Blocking NMDA-mediated neuronal excitation; potentiation of GABA mediated neurnal Na+ and Ca2+ channels; may be protective against hypoxic and ischemic neuronal damage
Name 2 possible adverse events with felbamate.
Potential hepatotoxicity (esp with pheno) May increased pheno levels, may cause KCS
Why is felbamate not used in cats?
Hepatotoxicity and blood dyscrasias (dcoumented in humans and dogs)
Which antionvulsant appears to have no appreciable hepatic metabolism?
Keppra (levetiracetam)
What is the MOA Of zonisamide?
Blockage of T-type Ca2+ and V-gated Na+ channels in brain
Faciliates dopaminergeric and serotonergic neurotransmission in CNS
Scavenging of free radicals
Enhancing action of GABA in brain
Inhibitiion of glutamate-mediated neronal excitation in brain
Inhibition of carbonic anhydrase activity
What potential adverse event has occurred with zonisamide?
Hepatotoxicity (rare) - metabolized by hepatic microsomal enzymes
Name viral causes of meningoencephalomyelitides.
Canine Distemper FIP Rabies CHV WNC Parvovirus Post-vaccine (rabies)
Name 3 dog breeds that get necrotizing mengingoencephalomyelitis?
Pugs
Maltese
Yorkies
What should you consider when you have a dog with multifocal neurologic signs?
Multifocal disease
What should you consider if involuntary, rhythmic jerking?
Distemper (also see extranural signs = foot pad and nose hyperkeratosis, rapid cachexia)
What should you consider if cervical rigidity/neck pain, acute fever, enutrophilia, massive pleocytosis?
Steroid0responsive meningitis arteritis (SRMA)
What should you consider in a pug with focal or generalized seizures?
Pug ME
What should you consider in a yorkie with brainstem signs = abnomral mentation, CN deficits, gait abnormalities?
Yorkie ME
What should you consider if you have a puppy 2-6 months old, acute onset, skull enlargement , forebrain signs (behavior change, blindness)?
Hydrocephalus with periventricular encephalitis
In with ME is fever most likley?
Bacterial infections and SRMA
What should be considered if your CSF reveals lymphoplasmacytic pleocytosis?
Vrial infections, chronic phase of SRMA, GME, and breed specific necrotizing encephalitis
What should be considered if your CSF reveals neutrophilic pleocytosis?
Bacterial infections and acute phase of SRMA
What should be considered if your CSF reveals mixed cell population?
Protozoal dz, FIP, chronic bacterial infection, necrotic lesions of GME
What should be considered if your CSF reveals eosinophils?
Rare eosinophilic encephalitis of unknown origin, protozoal, parasitic, mycotic infections, occasonally in GME and FIP
What is the classic finding on MRI of ME?
Hyperintense lesions in T2-weighted image (multifocal), contrast enhancing (not specific, other lesions can look this way too)
What can be seen if bacterial ME is suspected?
CSF often helpful (neutrophilic pleocytosis), clinical course rapid!, extranural lesions (sinusitis, otitis media)
What can be seen if viral encephalitis?
Mononuclear pleocytosis - Do antigen detection (PCR or IHC)
What is the ideal treatment for Toxoplasmosis and Neosporosis?
If muscle involvement = clindamycin
If CNS = TMS
Need at last 4-8 wks of treatment
What is the prognosis and treatment options for mycotic encephalitis?
POOR prognosis; long tx (9 months)
Cryptococcosis (cats and dogs) - Amphotericin B and fluconazole
What are the 2 most common events that result in cererovascular disease?
- Ischemia/infaraction
2. Hemorrhage
What is a cerebrovascular accident?
Stroke = Sudden onset of nonprogressive focla brain signs secondary to cerebrovascular disease
What is the penumbra in an ischemic stroke?
Tissue that has potential for recovery = target of interventional tx
Name possible underlyign diseases that can be seen in patients with ischemic stroke.
About 50% of cases dx based on MRI had other underlygin diseases
30% systemic hypertension = secondary to CKD or HAC
Name 2 dog breeds that are over-represented in ischemic strokes.
CKCS and Greyhounds
What percentage of ischemic strokes are cryptogenic?
about 50% - No underlyign cause = Brain infarct of unknown origin
What is a hemorrhagic stroke?
Blood leaks from vessel directly into brain = hematoma in parenchyma or subarachnoid space = mass causes physical disruption and pressur eon brain = Increased ICP and decreased CSF
How common is primary hemorrhagic stroke in dogs?
Rare in dogs
Name several secondary causes of hemorrhagic stroke in dogs.
Congenital vascular anomaly, brain tumors, inflamamtory dz of vessels, IV LSA, brain infarction, impaired coagulation
What is the classic presentation for an animal with cerebrovascular accident?
Usually abrupt onset of neurologic signs followed by arrest and then regression of deficits
What is the Monroe Kellie Doctrine?
Change in volume of one intracranial component (tissue, blood, etc) balanced by compensatory change in another = Exhaustion of this can result in herination
How is hyperventilation helpful in hemorrhagic stroke?
yperventilation is used to decreased ICP by causing hypocapneic vasconstriction (Need to monitor PCO2 closely, bc if excessively = decreased CBF)
What is the prognosis for cerebovacular events?
Variable - many revolve in weeks with only supportive care
No evidence that region of brain affects or type of infarction affects prognosis
Worse prognosis in dogs that had systemic disease, more likley to have recurrent infarcts/events