CSB332H1 Lecture Notes - Lecture 15: Middle Cerebral Artery, Internal Carotid Artery, Arterial Tree
14 May 2018
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Lecture 15(b): Stress & Stroke
Intracerebral Blood Flow & Death:
• The duration the blood flow is cut off to an area of the brain
determines severity of damage
o Intracerebral blood flow (ICBF) is a major determinant of
the infarct size
ð Ischemic zone that surrounds a central core of infarction with CBF
of 25% to 50% of normal and loss of autoregulation
o “central core of infarction” is the area that will definitely be
damaged by ischemia, but the area surrounding it (penumbra)
is repairable within a certain time frame
§ Viability of brain tissue is preserved if perfusion is restored within a critical
time period (3 hour rule)
• Where the thrombus or embolus is lodged is important
o Depending on where the occlusion occurs, it can
affect several parts of the brain
§ Middle cerebral artery supplies blood
to a large region of the brain is
particularly vulnerable
Embolic Stroke:
• Two common sources of emboli:
a) Left sided cardiac chambers – the atria/ventricles of the heart
b) Artery to artery stroke – piece of thrombus (plaque/clot) can break off from a blood
vessel and will be lodged in another area
§ Internal carotid artery (ICA) is often a site of plaque/thrombus formation
– clots will break off from this area and move into another blood vessel
ð Embolic strokes can result in ‘hemorrhagic’ strokes
Hypotensive Strokes:
• Any event that causes a sharp drop in blood pressure results in critical compromise of CBF
and delivery of oxygen and nutrients to neurons
o Sites usually affected by critically low CBF are located at the end of an arterial
territory – “watershed or boundary zone infarct” = end of the arterial tree
• Other areas that are vulnerable to ischemia are:
o Hippocampus: Pyramidal Cell Layer
o Cerebral Cortex: Purkinje Cell Layer
o Cerebellar Cortex
§ There areas use a lot of glutamate in their transmission; glutamate is an
excitotoxin and therefore are likely to undergo glutamatergic excitotoxicity
Reperfusion Injury [Secondary Stroke or Red Stroke]:
Document Summary
Lecture 15(b): stress & stroke: the duration the blood flow is cut off to an area of the brain determines severity of damage, intracerebral blood flow (icbf) is a major determinant of the infarct size. Ischemic zone that surrounds a central core of infarction with cbf of 25% to 50% of normal and loss of autoregulation. Central core of infarction is the area that will definitely be damaged by ischemia, but the area surrounding it (penumbra) is repairable within a certain time frame. Middle cerebral artery supplies blood to a large region of the brain is particularly vulnerable. Internal carotid artery (ica) is often a site of plaque/thrombus formation. Clots will break off from this area and move into another blood vessel. Embolic strokes can result in hemorrhagic" strokes. There areas use a lot of glutamate in their transmission; glutamate is an excitotoxin and therefore are likely to undergo glutamatergic excitotoxicity.
