A transient
ischaemic attack (TIA) is a temporary period
of disturbance of body function, lasting
for less than 24 hours, resulting from a
temporary reduction in blood supply to part
of the brain. About 50 000 people a year
in the UK experience a TIA.
Normal blood
supply to the brain can be obstructed by
material carried in the bloodstream (an
embolus) or by clotting of blood in an artery.
It is often called a 'mini-stroke'.
Transient
ischaemic attacks must always be taken seriously,
as they are a clear warning that a life-threatening
stroke may occur soon. They should always
be investigated, the cause found, and, if
possible, treated.
Without treatment,
about one in four people who have had a
TIA will have a stroke within the next few
years.
Symptoms
A TIA is a brief disturbance of any of the many
functions of the brain. So, a TIA may cause:·
- Brief
loss of half of the field of vision in
both eyes·
- Dizziness· Faintness·
- Vertigo·
- Confusion
of thought·
- Loss of
speech or of the understanding of the
meaning of words or of the names of objects·
- Weakness
or numbness of one side of the body·
- Forgetfulness·
- Temporary
loss of consciousness.
The disturbances
may take many forms, including weakness
in an arm or leg, numbness, pins and needles
on one side of the body, speech difficulty,
inability to name objects, obscured or partial
vision.
The type
of disturbance gives a clue to the area
of the brain affected and usually indicates
which arteries are involved.
One of the
most common effects is called Amaurosis
fugax. This is a temporary loss of vision,
usually for a few seconds or minutes, caused
by interference to the blood supply to parts
of the brain or eye.
The symptom,
which is entirely painless, may be an isolated
event or may occur many times a day. The
more often it occurs, the more serious the
situation.
Causes
The principal
underlying cause of both embolism and thrombosis
is the arterial disease atherosclerosis.
This is a degenerative disease of arteries
in which fatty plaques (atheroma) develop
on the inner lining so that the normal flow
of blood is reduced. Atherosclerosis
affects almost all of us, the earliest signs
being apparent in childhood, and in general
the condition becomes worse with age.
Two large
blood vessels, one on either side of the
neck, carry oxygenated blood up into the
head. Called the carotid arteries, they
branch into smaller blood vessels which
carry blood to all parts of the brain. If
one or more of these tiny blood vessels
gets clogged, by a blood clot or other debris,
the blood supply to nearby brain cells may
be disrupted. If this is temporary, a TIA
may occur. If the disruption to the blood
supply is permanent, it may result in a
stroke.
Sometimes
a TIA occurs when a blood clot from a blood
vessel in another part of the body, or from
the heart, moves upwards into one of the
brain's arteries. Very rarely, symptoms
of a TIA are due to bleeding (haemorrhage)
in the brain, or other causes.
Other causes
of, or contributory factors to, TIAs include
Anaemia, Leukaemia, Diabetes, raised blood
cholesterol levels, heart disease and abnormally
thickened blood (polycythaemia).
Treatment
Treatment
for TIA include controlling blood pressure
by altering diet and using drugs if necessary.
Often 'clot
busting' (anticoagulant) drugs may be used. These
drugs work by reducing the blood's ability
to form clots which can cause TIA and stroke.
Drugs used include Aspirin and Warfarin.
Even a quarter of an aspirin tablet (75mg)
can be enough to stop the attacks, although
it will not remove the root cause.
Where the
two main arteries to the brain have become
narrowed or blocked by disease, surgery
may be used clear the blockage and improve
blood flow.
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Transient Ischaemic Attack
