WEBVTT

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Strokes affect the brain.

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This organ needs high levels of energy
and lots of oxygen.

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Therefore,
it needs a very good supply of blood.

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During a stroke

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the blood flow to parts of the brain
is stopped.

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Most strokes are caused by a blood clot

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that blocks one of the arteries
supplying the brain with blood.

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• These clots can occur
within the brain itself,

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for example due to inflammatory lesions
in an artery wall.

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• However they more commonly develop
in another part of the body

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before being carried to the brain
through the circulatory system

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where they block an artery.

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Strokes that are caused by a blocked artery

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are referred to as ischemic strokes.

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The second, rarer cause of a stroke
is bleeding in the brain,

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for example
when a blood vessel is ruptured

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and blood leaks into the brain tissue.

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Regardless of the cause, the result

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is an area of the brain receiving
an inadequate supply of oxygen.

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Even a brief lack of oxygen

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causes nerve cells to die.

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The quicker it is treated

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and the oxygen supply restored,

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the higher the chances are

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that major damage to the brain
will be averted.

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Certain conditions
and genetic predispositions

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may increase the risk of having a stroke.

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These include, for example:

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• high blood pressure (hypertension)

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• persistent atrial fibrillation

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• and diabetes

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Other risk factors include:

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• smoking

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• excess weight

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• lack of exercise

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• and older age.

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Common indications of a stroke are:

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• sudden-onset debility

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• numbness and paralysis

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• slurred speech

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• visual field loss

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• dizziness

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• unsteady gait

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• and severe headaches.

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In most cases
only one side of the body is affected,

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for example the right arm or right leg
can no longer move properly.

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Other symptoms include nausea and vomiting.

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The precise way in which a stroke presents

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also depends
on which region of the brain is affected.

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Although strokes can be life-threatening

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many patients survive them.

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The consequences may be permanent,

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but often improve over time.

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In short:

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During a stroke the blood supply
to part of the brain is cut off.

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Strokes may be caused
by a blood vessel blocked

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by a blood clot or a burst blood vessel.

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This results in a lack of oxygen,

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causing nerve cells to die.

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The quicker it is treated,

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the likelier it is
that the consequences will be mild.

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Signs of a stroke are:

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• severe headaches
with particularly sudden onset,

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• paralysis or slurred speech.

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A stroke is always a medical emergency

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and the emergency services
must be called immediately.