Neuropathy of Cerebrovascular Disease Flashcards
What is the oxygen reserve capacity of the brain?
NONE-ZO.
NO BLOOD U DED (after 6-8 minutes)
Put the following cells in order of their sensitivity to ischemia: astrocytes, oligodendrocytes, neurons, endothelial cells
Neurons > oligodendrocytes > endothelial cells, astrocytes
Which neurons are particularly susceptible to ischemic damage?
Pyramidal cells in the CA1 region of the hippocampus
Which cells in the cerebellum are particularly susceptible to ischemic damage?
Purkinje cells
What is the definition of a stroke?
Abrupt onset of focal or global neurological symptoms caused by ischemia or hemorrhage
What are the two types of cerebrovascular disease?
Cerebral ischema: 85% (can be global or focal)
Intracranial hemorrhage: 15%
What causes an intraparenchymal hemorrhage?
HTN, amyloid
What causes a subarachnoid hemorrhage?
Saccular aneurysms, AVM
Name 4 causes of global cerebral ischemia
1) Low perfusion (due to atherosclerosis)
2) Acute decrease in blood flow (cardiogenic shock)
3) Chronic hypoxia (anemia)
4) Repeated episodes of hypoglycemia (insulinoma)
What are the consequences of mild global ischemia?
No permanent damage
What are the consequences of severe global ischemia?
diffuse damage –> vegetative state
What are the consequences of moderate global ischemia?
Damage to watershed areas and selectively vulnerable regions
What microscopic changes occur in the first 6 hours of ischemia to the brain?
None
When do “red dead neurons” appear following infarction and what are their characteristics?
Cytoplasmic eosinophilia
Loss of Nissl substance
Dark pyknotic nuclei
What is laminar necrosis?
Selective vulnerability of the pyramidal neurons of layers 3 and 5 leads to laminar necrosis (specific layers of the cortex die)
This only occurs if the patient survives longer than 3 days…
In adult brains, big neurons, neurons in cortical layers 3 and 5, CA1 of the hippocampus and purkinje cells of the cerebellum are selectively vulnerable to ischemic damage. Which cells are vulnerable in the infant brain?
Subiculum, thalamus, and pontine nuclei
WHat is the most common cause of thrombotic focal ischemia in the brain?
atherosclerosis
Where does atherosclerotic plaque build up/rupture most often occur in the brain?
The junction of the bifurcation of the internal carotid arteries and the MCA
WHat is the most common cause of embolisms to the brain?
Cardioembolic- atrial fibrillation is the most common cause
Where in the vasculature do cardioembolic plaques tend to lodge?
The MCA
Name three small vessel diseases that can affect the brain
Diabetes, atherosclerosis, vascultits
Infarction of which arteries leads to lacunar strokes?
Lenticulostriate vessels
Ischemia to the internal capsule leads to what type of stroke (as in what type of information is disrupted)
Pure motor stroke
Ischemia to the thalamus leads to what type of stroke (as in what type of information is disrupted)?
Pure sensory stroke
Following ischemic damage in the MCA territory of the brain, dominant hemisphere infarct and non-dominant infarct are associated with different symptoms. Differentiate between dominant and non-dominant hemispheric symptoms.
Dominant hemisphere infarct is often associated expressive aphasia (inability to produce language) whereas non-dominant infarct is associated with neglect syndrome
What gross changes are seen following an acute infarct (6-48 hours)
pale, soft, swollen, indistinct border, blurred grey/white junction
Which areas of the brain are susceptible to lacunar infarct?
basal ganglia, thalamus, pons and subcortical white matter
What are two major causes of lacunar infarcts?
HTN, Small Vessel Disease
What is the most common cause of a hemorrhagic cerebral infarction?
Embolism – it is secondarily hemorrhagic following reperfusion
What is the cause of intracranial hemorrhages above the arachnoid (epidural and subdural hematomas)
Trauma
What is the cause of intracranial hemorrhages below the arachnoid (subarachnoid)?
Underlying cerebral vascular disease
What causes a subarachnoid hemorrhage?
Aneurysms
What causes an intraparenchymal hemorrhage?
Hypertension
Name 4 common locations of a hypertensive hemorrhage.
putamen, pons, thalamus, cerebellum
What are Charcot-Bouchard aneurysms?
Aneurysms associated with chronic HTN. They affect small blood vessels (such as in the basal ganglia and thalamus)
Resolution of an intraparenchymal hemorrhage?
Resolution leaves a small cystic space with macrophages containing hemosiderin
Where do most saccular (berry) aneurysms occur?
In the anterior circle of willis
In what population does intraventricular hemorrhages occur?
Common in premature infants (and instantly fatal)
Very rare in adults
Where is the site of rupture of an intraventricular hemorrhage?
In the germinal matrix located beneath the ependyma which easily ruptures into the ventricles
Where does a Duret hemorrhage occur?
In the pons
A duret hemorrhage is secondary to what event?
Secondary to compression from herniation of the medial temporal lobe that leads to stretching and ischemia of perforating arterioles
Compression can result from a variety of mass lesions producing herniation:
hemorrhages, inflammation, neoplasms
What is a lethal complication of an epidural hematoma?
Herniation
What causes a subdural hematoma?
Tearing of bridging veins between dura and arachnoid
What is the difference between an epidural and subdural bleed on CT?
Epidural: lens shaped bleed
Subdural: crescent shaped bleed
What is a lethal complication of a subdural bleed?
Herniation
What is a deadly consequence of a tonsillar herniation?
Compression of the brainstem and cardiopulmonary arrest
What is a subfalcine herniation?
Displacement of the cingulate gyrus under the falx cerebri
What structure is compressed by a subfalcine herniation
The ACA
Compression of the ACA leads to infarction
What is an uncal herniation?
Displacement of the uncus (of the median temporal lobe) under the tentorium cerebelli
What structures are compressed by an uncal herniation?
CN III –> Down and out eye + dilated pupil
Compression of PCA leads to occipital lobe infarct (contralateral homonymous hemianopsia)
Rupture of the paramedian artery –> Duret hemorrhages
What are the microscopic changes that occur 1-2 weeks post infarct?
Reactive gliosis and vascular proliferation
