STUTTERING
S
TYPES AND CAUSES OF STROKE
Stroke may be caused by any of three mechanisms (below):
cerebral thrombosis, cerebral embolism, or haemorrhage .
Thrombosis and embolism both lead to cessation of the
blood supply to part of the brain and thus to infarction
(tissue death). Rupture of a blood vessel in or near the brain
may cause an intracerebral haemorrhage or a subarachnoid
haemorrhage. Any part of the brain may be affected by a
stroke; accordingly the symptomsvary considerably.
CEREBRAL THROMBOSIS
CEREBRAL EMBOLISM
HAEMORRHAGE
Area
deprived
o f blood
Thrombus
blocks
artery
Thrombosis
Blockage by a
thrombus (clot) that
has built up on the
wall of a brain artery
accounts for 40 to 50
per cent ofstrokes.
Area
deprived of
blood
Embolism
Blockage by an
embolus (usuallya
clot) swept into an
artery in the brain
accounts for 30 to 35
per cent of strokes.
Area of
bleeding
Bleeding
Rupture of a blood
vessel and bleeding
within or over the
surface ofthe brain
accounts for 20 to 25
per cent of strokes.
Age
<45
45-54
55-64
65-74
75-84
>84
Key
• Cerebral
infarction
• Intracerebral
haemorrhage
• Subarachnoid
haemorrhage
Incidence with age
Strokes are rare under age 45. Incidence of
incidence of intracerebral haemorrhage and
cerebral infarction increases with age, but
subarachnoid haemorrhage falls after age 75.
Cerebral
haemorrhage
This CT (computed
tomography) scan
shows a subdural
haematoma. The left
side ofthe brain
(right on image) is
filled with blood,
which has clotted to
form a solid mass.
Haematoma
SYMPTOMS
The symptoms of a stroke usually
develop abruptly over minutes or
hours, but occasionally over several
days. Depending on the size, site,
cause, and extentofdamage, any or
all ofthe symptoms shown on the
right may be present, in anydegree
ofseverity. A serious stroke may
lead to rapid loss ofconsciousness,
coma, and death. Up to 30 per cent
of people are dependent on others
after stroke, but some strokes
cause barely noticeable symptoms.
Hemiplegia
Weakness, paralysis, or loss of sensation on
one side ofthe body are the more common
effects of a serious stroke.
Headache
Dizziness and
confusion
Visual
disturbance
Slurred speech
or loss
ofspeech
Difficulty in
swallowing
RISK FACTORS
Age
High blood pressure
Atherosclerosis (narrowing
of arteries by fatty deposits)
Heart disease
Diabetes mellitus
Smoking
Polycythaemia
Hyperlipidaemia
Obesity
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