Ischemic stroke:
Ischemic stroke, which accounts for about 85% of stroke cases, occurs when blood
flow in the blood vessels that supply the brain is blocked or reduced. This blockage
results in an insufficient supply of oxygen and nutrients to brain tissue. The two main
causes of ischemic stroke are:
A. Thrombotic Stroke:
It occurs when a blood clot (thrombus) forms in a blood vessel, often due to
atherosclerosis (plaque buildup) in the arteries that supply blood to the brain.
B. Embolic stroke:
This is because blood clots and other debris (emboli) form elsewhere in the body
(common in the heart), travel through the bloodstream, and eventually block an
artery in the brain, causing blood to flow to the brain. Occurs when flow is
interrupted.
Hemorrhagic stroke:
A hemorrhagic stroke occurs when there is bleeding in or around the brain, causing
compression or damage to brain tissue. Hemorrhagic stroke has two main types:
A. Cerebral hemorrhage:
This is bleeding directly into the brain tissue and is usually caused by rupture of
weakened blood vessels caused by years of high blood pressure or cerebral amyloid
angiopathy.
B. subarachnoid hemorrhage:
It is bleeding into the space between the brain and surrounding membranes (the
subarachnoid space) and is most commonly caused by a ruptured brain aneurysm or
arteriovenous malformation (AVM).
Common pathophysiological processes in stroke:
Ischemia:
Both ischemic and hemorrhagic stroke result in decreased oxygen and glucose
supplies to brain cells due to interruption of blood flow, leading to cellular
dysfunction and eventual cell death.
Cerebral edema:
After a stroke, inflammation and cell damage can cause fluid to accumulate in the
brain, leading to cerebral edema. Increased intracranial pressure due to edema may
further inhibit blood flow and cause secondary brain injury.
Excitotoxicity:
Ischemia causes excessive release of excitatory neurotransmitters (such as
glutamate) in the brain. This hyperexcitation results in an influx of calcium into
neurons, leading to cytotoxic damage and neuronal death.
Formation of free radicals:
Ischemic stroke, which accounts for about 85% of stroke cases, occurs when blood
flow in the blood vessels that supply the brain is blocked or reduced. This blockage
results in an insufficient supply of oxygen and nutrients to brain tissue. The two main
causes of ischemic stroke are:
A. Thrombotic Stroke:
It occurs when a blood clot (thrombus) forms in a blood vessel, often due to
atherosclerosis (plaque buildup) in the arteries that supply blood to the brain.
B. Embolic stroke:
This is because blood clots and other debris (emboli) form elsewhere in the body
(common in the heart), travel through the bloodstream, and eventually block an
artery in the brain, causing blood to flow to the brain. Occurs when flow is
interrupted.
Hemorrhagic stroke:
A hemorrhagic stroke occurs when there is bleeding in or around the brain, causing
compression or damage to brain tissue. Hemorrhagic stroke has two main types:
A. Cerebral hemorrhage:
This is bleeding directly into the brain tissue and is usually caused by rupture of
weakened blood vessels caused by years of high blood pressure or cerebral amyloid
angiopathy.
B. subarachnoid hemorrhage:
It is bleeding into the space between the brain and surrounding membranes (the
subarachnoid space) and is most commonly caused by a ruptured brain aneurysm or
arteriovenous malformation (AVM).
Common pathophysiological processes in stroke:
Ischemia:
Both ischemic and hemorrhagic stroke result in decreased oxygen and glucose
supplies to brain cells due to interruption of blood flow, leading to cellular
dysfunction and eventual cell death.
Cerebral edema:
After a stroke, inflammation and cell damage can cause fluid to accumulate in the
brain, leading to cerebral edema. Increased intracranial pressure due to edema may
further inhibit blood flow and cause secondary brain injury.
Excitotoxicity:
Ischemia causes excessive release of excitatory neurotransmitters (such as
glutamate) in the brain. This hyperexcitation results in an influx of calcium into
neurons, leading to cytotoxic damage and neuronal death.
Formation of free radicals:
