Neuroscience Week 6: Cerebrovascular disease Flashcards
Overview
Objectives
Cerebrovascular diseases overview
Identify
15-20%
Identify
- third most common
- serious disabilities
Identify
ischemic necrosis (infarction) or hemorrhage
Cerebrovascular events (strokes) result from?
- locally occlusive vascular disorders
- reduction in systemic perfusion or oxygenation
- hemorrhage
Describe cerebral perfusion
- brain perfusion is heavily regulated
- MAP doesnt change between 50 - 100 mmHg
- also depends on concentration of CO2
- when conc of PCO2 increases you have an increase in cerebral blood flow until 90mmhg
- when O2 falls below 50mmhg there is an increase in cerebral blood flow
- (tries to prevent hypoxia)
Strategies to treat acute cerebral edema
Therapeutic hyperventilation
when ↓ PCO2 there is vasoconstriction which ↓ cerebral blood flow → ↓intracranial pressure (ICP)
Therapeutic hyperventilation can be used to treat?
- acute cerebral edema
- when ↓ PCO2 there is vasoconstriction which ↓ cerebral blood flow → ↓intracranial pressure (ICP)
Global Cerebral Ischemia Causes
Caused by severe systemic hypotension (systolic blood pressure falls below 50 mmHg) secondary to cardiac arrest or shock
Global Cerebral Ischemia which cells are more susceptible
- Neurons are more susceptible than glial cells
- The pyramidal neurons in the hippocampus and neocortex are particularly vulnerable
- as are the Purkinje cells in the cerebellum
Describe Severe Global Cerebral Ischemia
- widespread neuronal death occurs
- survivors will have severe neurological deficits (vegetative state or brain death)
- All voluntary and brainstem reflex functions are absent requiring mechanical ventilation
- the brain undergoes autolysis
Global Cerebral Ischemia Overview
Global Cerebral Ischemia Gross Morphology
Swollen brain with wide gyri and narrowed sulci
Global Cerebral Ischemia Histology: Early changes (12-24 hours)
3 listed
Early changes (12-24 hours)
- cystoplasmic eosinophilia (red neurons)
- nuclear pyknosis and fragmentation
- Glial cell damage also occurs and neutrophil infiltration
Global Cerebral Ischemia Histology: Subacute changes (24hrs-2 weeks)
- Necrosis
- macrophage infiltration
- vascular proliferation
- reactive gliosis
Global Cerebral Ischemia Histology: Repair (2 weeks)
removal of necrotic tissue and gliosis
Identify
Global Cerebral Ischemia
infiltration of cerebral infarction by neutrophils begins at the edges of the lesion where the vascular supply is intact
Identify
Global Cerebral Ischemia
By day 10, an area of infarction shows the presence of macrophages and surrounding reactive gliosis
Identify
Global Cerebral Ischemia
Old intracortical infarcts are seen as areas of tissue loss and residual gliosis
Identify
Global Cerebral Ischemia
A. infiltration of cerebral infarction by neutrophils begins at the edges of the lesion where the vascular supply is intact
B. By day 10, an area of infarction shows the presence of macrophages and surrounding reactive gliosis
C. Old intracortical infarcts are seen as areas of tissue loss and residual gliosis
Identify
Global Cerebral Ischemia Watershed Infarcts
Identify
Watershed infarction at MCA/PCA territory
Identify
Watershed infarction at ACA/MCA territory
Embolic Infarctions Common Causes
3 listed
- Cardiac mural thrombi are frequent cause of emboli (e.g. in patients with atrial fibrilation, myocardial infarction or valvular disease).
- Thromboemboli can also originate in carotid atheromatous plaques
- Venous emboli can cross into the arterial circulation via a patent foramen ovalae (deep venous thrombosis of legs or fat embolism)
Embolic Infarctions commonly affect which vessel
Commonly affect MCA
Thrombotic Occlusions Common Causes
2 listed
- Superimposed on atherosclerotic plaques in carotid bifurcation, MCA origin, and ends of the Basilar artery
- can also be caused by hypertension-induced thrombotic occlusions of small penetrating arteries (lacunar infarcts)
Acute non-hemorrhagic infarcts can?
Evolve into hemorrhagic infarcts
especially when there is reperfusion of ischemic tissue (either through collaterals or after emboli have dissolved)
Focal Cerebral Ischemia Examples
3 listed