The brain controls many functions through its three main parts - the cerebrum, cerebellum, and brain stem. The cerebrum controls thinking and movement. The cerebellum controls coordination and balance. The brain stem connects to the spinal cord and controls automatic functions. The brain receives a rich blood supply through arteries to power its billions of cells. Different regions of the cortex are linked to specific functions like senses, thoughts, and memory. Stroke occurs when blood flow to the brain is disrupted, causing cells to die from lack of oxygen. The two main types are ischemic, from blockage, and hemorrhagic, from bleeding.

2. Review of Anatomy
The brain is the most powerful organ, yet weighs only about three pounds.
It has a texture similar to firm jelly and has three main parts; cerebrum, cerebellum, and the
brain stem.
The cerebrum fills up most of the skull and is involved in remembering, problem solving,
thinking, feeling, as well as control movement.
The cerebellum sits at the back of the head, under the cerebrum and it controls coordination
and balance
The brain stem sits beneath the cerebellum, connects to the spinal cord and controls autonomic
functions such as breathing, digestion, heart rate, and blood pressure.
The brain is nourished by one of the body’s richest networks of blood vessels.
With each heartbeat, arteries carry about 20% to 25% of blood to the brain, where billions of
cells use about 20% the oxygen and fuel the blood carries
When thinking hard, the brain may use up to 50% of the fuel and oxygen
The whole vessel network includes veins and capillaries in addition to arteries.

3. • The brain’s wrinkled surface is a specialized outer layer of the
cerebrum called the cortex. Scientists have “mapped” the cortex by
identifying areas strongly linked to certain functions
• Specific regions of the cortex:
• Interpret sensations from the body, and sights, sounds and smells
from the outside world.
• Generate thoughts, solve problems and make plans.
• Forms and stores memories.
• Control voluntary movements.

4. • The brain is divided into right and left halfs.
• The left half controls the right side of the body
• The right half controls the body’s left

5. • The real network of the brain goes on in individual cells. An adult
brain contains about 100 billion nerve cells, of neurons, with
branches that connect at more than 100 trillion points. Scientists call
this dense, branching network a “neuron forest.”
• Signals traveling through the neuron forest form the basis of
memories, thoughts, and feelings.

6. • Signals that form memories and thoughts move through an individual
nerve cell as a tiny electrical charge.
• Nerve cells connect to one another at synapses. When a charge
reaches a synapse, it may trigger release a tiny bursts of chemicals
called neurotransmitters. The neurotransmitters travel across the
synapse, carrying signals to another cells.

7. Cerebrovascular Accident - CVA
• Also known as stroke, brain attack, acute ischemic cerebrovascular
syndrome.
• Occurs when blood supply to part of the brain is disrupted, causing
brain cells to die. When blood flow to the brain is impaired, oxygen
and glucose cannot be delivered to the brain. Blood flow can be
compromised by a variety of mechanisms;
• A neurological deficit of cerebrovascular cause that persists beyond
24 hours or is interrupted by death within 24 hours - WHO

8. Mechanisms that compromise the blood flow
to the brain
Blockage of an artery
• Arteriosclerosis – hardening of the arteries leading to the brain
• Atherosclerosis – arteries become narrow because of a plaque or
cholesterol
• Embolism to the brain from the heart

9. • Rapture of an artery (hemorrhage)
• Cerebral hemorrhage – bleeding within the brain substance. The most
common reason to have bleeding within the brain is uncontrolled
high blood pressure.
• Other situations include aneurysms that leak or rupture or
arteriovenous malformations (AVM) in which there is an abnormal
collection of blood vessels that are fragile and can bleed.

10. Classification of stroke
• By blood vessels
• Burst vessel – a blood vessel bursts, accounting fot 20% of strokes
• Clogged vessel – a blood clot forms, accounting for 80% of strokes.

11. Ischemic Stroke
• Blood supply to parts of the brain is decreased, leading to dysfunction
and necrosis of brain tissue in that area. This may be due to:
a) Thrombosis – obstruction of blood vessel by a blood cloth forming locally
b) Embolism – an embolus from elsewhere in the body
c) Systemic hypoperfusion – general decrease in blood supply, e.g. in shock
d) Stroke without an obvious explanation (cryptogenic) – of unknown origin.

12. Types of Ischemic Stroke
Thrombotic Stroke (large & small vessel diseases)
• Here, a thrombus (blood clot) usually forms around atherosclerotic
plaques. Since blockage of the artery is gradual, onset of symptoms is
slower.
• A thrombus itself (even if non-occluding) can lead to an embolic
stroke, if the thrombus breaks off, at which point it is called an
“embolus.”
• Sickle cell amemia, which can cause blood cells to clump up an block
vessels can lead to stroke. Stroke is the second leading cause of death
in people under 20 who suffer from sickle cell anaemia.

13. • Embolitic Stroke – blockage of an artery by an embolus, a traveling
particle or debris in the arterial bloodstream originating from
elsewhere.
• An embolus is most frequently a thrombus, but it can also be a
number of other substances.
• Since an embolus arise from elsewhere, local therapy only solves the
problem temporary. Thus, the source of the embolus must be
identified.
• Embolitic blockage is sudden in onset, symptoms usually are minimal
at start. Also, symptoms may be transient an the embolus is partially
reabsorbed and moves to a different location or dissipates altogether.