Week 8.4 Flashcards
Neurons begin suffering irreversible after what duration of anoxia?
5-6 minutes
What are some causes of global brain ischemia?
- suffocation
- poisoning
- hypotension
- cardiac arrest
Which adult brain structures are mot susceptible to ischemia?
- CA1 of hippocampus
- Purkingje Cells
- Pyramidal Neurons in layers 3, 5, and 6
What important structure is located within the ACA/MCA watershed zone?
the hippocampus
What are four significant causes of focal ischemia?
- thrombosis
- embolus
- vasculitis
- CADASIL
Where in the cerebral vasculature are thrombi most common?
- carotid bifurcation
- middle cerebral artery origin
- top and bottom of basilar arter
What are the most common sources of embolus to the brain?
- heart
- carotids
- paradoxical
- fat, tumor, air
Paradoxical emboli travel through a patent ___.
foramen ovale
Emboli are most likely to lodge in which cerebral artery?
the MCA
What is an hemorrhagic infarct?
an ischemic event gets broken up and hemorrhage follows as RBCs leak through damaged endothelial cells causing petechial hemorrhages
What gross changes can you expect following ischemia?
- 0-6 hours: nothing
- 48 hours: pale, soft, swollen
- 2-10 days: friable, demarcation
- 10-21 days: liquefaction
What microscopic changes can you expect following ischemia?
- 12-24 hours: red neurons
- 12-48 hours: neutrophils
- 48 hours - 2 weeks: macrophages, necrosis
- 1 - 4 weeks: astrocytic proliferation
- chronic: glial scar, cyst, Wallerian degeneration
Name four possible causes of cerebral edema.
- tumor
- infarct/hemorrhage
- abscess
- diffuse axonal injury
Why is subfalcine herniation problematic?
it tends to compress the ACA
Why is transtentorial herniation problematic?
- compresses CN III
- compresses PCA causing occipital lobe infarction
- causes hemorrhages in brainstem
What is CADASIL?
aka cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, an autosomal dominant vascular dementia caused by Notch3 mutation
What causes CADASIL?
a notch3 mutation
What are the features of CADASIL?
- onset in 20s-30s with migraine with aura
- depression
- recurrent infarcts leading to cognitive decline and dementia
What histologic evidence supports CADASIL?
PAS staining of vessels in a skin biopsy
What are lacunar infarcts?
small, subcortical infarcts
The most common cause of lacunar infarcts is what?
hypertensive CV disease and the resulting arteriolar sclerosis
Hypertensive CV disease affects predominant which brain structures?
deep nuclei and white mater
What are the three most common places for lacunar infarcts?
- putamen/globus pallidus
- thalamus
- internal capsule
The most common cause of intraparenchymal hemorrhage is what?
hypertension
How does hypertension lead to intraparenchymal hemorrhage?
- hypertension
- accelerated atherosclerosis
- hyaline arteriosclerosis
- increased fragility
- formation of microscopic aneurysms
- rupture
What are Charcot-Bouchard aneurysms?
hypertension induced microaneurysms
What are the most common sites of intraparenchymal hemorrhage?
- putamen
- thalamus
- pons
What is the primary complication of cerebral amyloid angiopathy?
cerebral hemorrhage
What would cause a fat emboli?
long bone trauma
What is amyloid?
an misfolded protein in a beta-sheet
How can we identify amyloid on a stained section of tissue?
using congo red stain and polarized light
The three most significant vascular malformations are what?
- AVM
- cavernous angioma
- capillary telangiectasia
What is a cavernous angioma?
a venous abnormality in which hyalinized vessels are back-to-back
What is capillary telangiectasia?
dilated thin-walled vessels separated by normal brain tissue
Why are AVMs a problem?
- the strain the heart
- the are mass-occupying
- they act as a shunt for oxygen
- the high pressure input to veins can rupture them
What are the two major complications of cavernomas?
- seizures
- cerebral hemorrhage
Berry aneurysms cause what kind of hemorrhage?
subarachnoid
What are major risk factors for subarachnoid hemorrhage?
- hypertension
- smoking
- genetics (Marfan’s, NF1, etc.)
Where are Berry aneurysms most common?
- anterior communicating artery
- middle cerebral artery (distal and proximal)
Subdural hemorrhage is followed by what sort of reorganization?
fibroblasts wall off the blood until it can be resorbed
Which organisms most commonly cause brain abscesses?
staphylococci and streptococci
Describe abscess organization.
- center of necrosis and neutrophils
- rim of granulation tissue and a fibrous capsule
- surrounded by edema and gliosis
Brain abscesses often mimic what other pathology?
glioblastoma
Taxoplasmosis is transmitted by what species?
cats
What virus most commonly causes meningitis?
enteroviruses
What are the typical features of viral encephalitis?
- perivascular chronic inflammation
- microglial nodules
- neuronophagia
- viral inclusions
How does rhabdovirus enter the CNS?
via intraaxonal retrograde transport
Negri bodies are a feature of which CNS infection?
rhabies
How is a diagnosis of HIV encephalitis made?
the presence of multinucleate giant cells in microglial nodules that stain for HIV p24
